diff --git a/THEME.md b/THEME.md
new file mode 100644
index 0000000..b0884ef
--- /dev/null
+++ b/THEME.md
@@ -0,0 +1,189 @@
+# Theme System
+
+## Overview
+
+The application uses a centralized CSS custom properties (variables) system defined in `src/theme.css`. This provides a consistent design language across all components and makes theme switching possible in the future.
+
+## Architecture
+
+### Theme Variables
+
+All theme variables are defined at the `:root` level in `theme.css` and use the `--` prefix:
+
+```css
+:root {
+  --color-accent-primary: #646cff;
+  --space-md: 0.75rem;
+  --font-base: 0.875rem;
+}
+```
+
+### Usage in Components
+
+Components reference theme variables using `var()`:
+
+```css
+.my-component {
+  color: var(--color-text-primary);
+  padding: var(--space-md);
+  font-size: var(--font-base);
+}
+```
+
+## Variable Categories
+
+### Colors
+
+#### Base & Surface
+- `--color-bg-base`: Main background
+- `--color-surface-0` through `--color-surface-3`: Elevated surfaces
+
+#### Text Hierarchy
+- `--color-text-primary`: Main text (87% opacity)
+- `--color-text-secondary`: Secondary text (60% opacity)
+- `--color-text-tertiary`: Labels and hints (40% opacity)
+- `--color-text-disabled`: Disabled state (25% opacity)
+
+#### Accent
+- `--color-accent-primary`: Primary brand color (#646cff)
+- `--color-accent-primary-hover`: Hover state
+- `--color-accent-primary-subtle`: Transparent accent for backgrounds
+
+#### Semantic
+- `--color-success`: Success states (#10b981)
+- `--color-warning`: Warning states (#fbbf24)
+- `--color-error`: Error states (#ef4444)
+- `--color-info`: Informational elements (#60a5fa)
+
+#### Borders
+- `--color-border-subtle`: Very subtle borders (6% opacity)
+- `--color-border-default`: Standard borders (10% opacity)
+- `--color-border-strong`: Emphasized borders (20% opacity)
+
+#### Interactive States
+- `--color-hover-overlay`: Hover effect
+- `--color-active-overlay`: Active/pressed effect
+- `--color-selected-overlay`: Selection background
+
+### Spacing
+
+Uses a consistent scale from `--space-xs` (0.25rem) to `--space-2xl` (2rem):
+
+```
+xs:  0.25rem
+sm:  0.5rem
+md:  0.75rem
+lg:  1rem
+xl:  1.5rem
+2xl: 2rem
+```
+
+### Typography
+
+#### Font Sizes
+- `--font-xs` through `--font-lg` for consistent sizing
+- Base size is `--font-base: 0.875rem`
+
+#### Font Families
+- `--font-mono`: Monospace font for code
+- `--font-sans`: System UI font
+
+#### Line Heights
+- `--leading-tight`: 1.4
+- `--leading-normal`: 1.5
+- `--leading-relaxed`: 1.6
+
+### Visual Effects
+
+- `--radius-sm/md/lg`: Border radius values
+- `--shadow-sm/md/lg`: Box shadow presets
+- `--transition-fast/base/slow`: Animation durations
+
+### Component-Specific
+
+Specialized tokens for specific use cases:
+- `--accordion-*`: Accordion styling
+- `--input-*`: Form inputs
+- `--tooltip-*`: Tooltip components
+- `--code-*`: Code blocks
+
+## Design Principles
+
+### Color Usage
+
+1. **Use accent colors sparingly**: Primary accent (#646cff) for:
+   - Interactive elements
+   - Primary actions
+   - Highlighted content (e.g., opcode names)
+
+2. **Semantic colors for meaning**:
+   - Blue (`--color-info`) for informational data (e.g., rates)
+   - Green (`--color-success`) for success states
+   - Yellow (`--color-warning`) for warnings
+   - Red (`--color-error`) for errors
+
+3. **Text hierarchy through opacity**:
+   - Use `--color-text-*` variables instead of custom opacity values
+   - Maintains consistency and improves readability
+
+### Spacing
+
+- Use the spacing scale consistently
+- Avoid magic numbers - use defined spacing tokens
+- Vertical rhythm: prefer consistent spacing between elements
+
+### Borders
+
+- Most borders should use `--color-border-subtle` for minimal visual weight
+- Use `--color-border-default` for more emphasis
+- Reserve `--color-border-strong` for important separators
+
+## Adding a New Theme
+
+To add a new theme (e.g., light mode):
+
+1. Create a new CSS file (e.g., `theme-light.css`)
+2. Override the root variables:
+
+```css
+:root {
+  --color-bg-base: #ffffff;
+  --color-text-primary: rgba(0, 0, 0, 0.87);
+  /* ... other overrides */
+}
+```
+
+3. Conditionally import based on theme preference
+4. All components automatically adapt to the new values
+
+## Migration Guide
+
+When updating existing components to use the theme system:
+
+### Before
+```css
+.component {
+  background-color: #1a1a1a;
+  color: rgba(255, 255, 255, 0.87);
+  padding: 0.75rem;
+  border: 1px solid #3a3a3a;
+}
+```
+
+### After
+```css
+.component {
+  background-color: var(--color-bg-base);
+  color: var(--color-text-primary);
+  padding: var(--space-md);
+  border: 1px solid var(--color-border-default);
+}
+```
+
+## Benefits
+
+1. **Consistency**: Single source of truth for design tokens
+2. **Maintainability**: Change once, apply everywhere
+3. **Theme switching**: Easy to add light/dark mode or custom themes
+4. **Readability**: Semantic names instead of magic values
+5. **Scalability**: Add new tokens without touching components
diff --git a/index.html b/index.html
index 4c3f06d..e4aa5bc 100644
--- a/index.html
+++ b/index.html
@@ -2,9 +2,10 @@
 <html lang="en">
   <head>
     <meta charset="UTF-8" />
-    <link rel="icon" type="image/svg+xml" href="/vite.svg" />
+    <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <title>oldboy</title>
+    <meta name="description" content="Online Csound Editor - Write, compile, and perform Csound code in your browser" />
+    <title>Online Csound Editor</title>
   </head>
   <body>
     <div id="app"></div>
diff --git a/package.json b/package.json
index 83f5a22..0529f05 100644
--- a/package.json
+++ b/package.json
@@ -38,6 +38,7 @@
     "@codemirror/view": "^6.38.6",
     "@csound/browser": "7.0.0-beta11",
     "@hlolli/codemirror-lang-csound": "1.0.0-alpha10",
+    "@lezer/highlight": "^1.2.1",
     "@replit/codemirror-vim": "^6.3.0",
     "codemirror": "^6.0.2",
     "fuse.js": "^7.1.0",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 1c82994..66fb91a 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -50,6 +50,9 @@ importers:
       '@hlolli/codemirror-lang-csound':
         specifier: 1.0.0-alpha10
         version: 1.0.0-alpha10(@codemirror/language@6.11.3)(@codemirror/state@6.5.2)(@codemirror/view@6.38.6)(codemirror@6.0.2)
+      '@lezer/highlight':
+        specifier: ^1.2.1
+        version: 1.2.1
       '@replit/codemirror-vim':
         specifier: ^6.3.0
         version: 6.3.0(@codemirror/commands@6.9.0)(@codemirror/language@6.11.3)(@codemirror/search@6.5.11)(@codemirror/state@6.5.2)(@codemirror/view@6.38.6)
diff --git a/public/favicon.svg b/public/favicon.svg
new file mode 100644
index 0000000..7564243
--- /dev/null
+++ b/public/favicon.svg
@@ -0,0 +1,14 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32" fill="none">
+  <rect width="32" height="32" fill="#1a1a1a"/>
+  <path d="M 4 16 Q 6 12, 8 16 T 12 16 T 16 16 T 20 16 T 24 16 T 28 16"
+        stroke="#646cff"
+        stroke-width="2"
+        fill="none"
+        stroke-linecap="round"/>
+  <path d="M 4 20 Q 7 14, 10 20 T 16 20 T 22 20 T 28 20"
+        stroke="#646cff"
+        stroke-width="1.5"
+        fill="none"
+        opacity="0.6"
+        stroke-linecap="round"/>
+</svg>
diff --git a/src/App.svelte b/src/App.svelte
index 8467f3a..25b80af 100644
--- a/src/App.svelte
+++ b/src/App.svelte
@@ -237,6 +237,13 @@
     }
   }
 
+  $effect(() => {
+    const theme = $editorSettings.theme;
+    if (typeof document !== 'undefined') {
+      document.documentElement.dataset.theme = theme;
+    }
+  });
+
   $effect(() => {
     if (uiState.scopePopupVisible || uiState.spectrogramPopupVisible) {
       analyserNode = csound.getAnalyserNode();
@@ -343,16 +350,16 @@
       </button>
     {/snippet}
     <button
-      onclick={() => uiState.openScope()}
+      onclick={() => uiState.toggleScope()}
       class="icon-button"
-      title="Open audio scope"
+      title="Toggle audio scope"
     >
       <Activity size={18} />
     </button>
     <button
-      onclick={() => uiState.openSpectrogram()}
+      onclick={() => uiState.toggleSpectrogram()}
       class="icon-button"
-      title="Open spectrogram"
+      title="Toggle spectrogram"
     >
       <svg
         width="18"
@@ -546,20 +553,20 @@
   }
 
   .icon-button {
-    padding: 0.5rem;
-    background-color: #333;
-    color: rgba(255, 255, 255, 0.87);
+    padding: var(--space-sm);
+    background-color: var(--color-border-default);
+    color: var(--color-text-primary);
     border: 1px solid #555;
     cursor: pointer;
     display: flex;
     align-items: center;
     justify-content: center;
-    transition: background-color 0.2s;
+    transition: background-color var(--transition-base);
   }
 
   .icon-button:hover:not(:disabled) {
     background-color: #444;
-    border-color: #646cff;
+    border-color: var(--color-accent-primary);
   }
 
   .icon-button:disabled {
@@ -568,7 +575,7 @@
   }
 
   .icon-button.has-changes {
-    color: #646cff;
+    color: var(--color-accent-primary);
   }
 
   .icon-button.stop-button:not(:disabled) {
@@ -582,18 +589,18 @@
 
   h3 {
     margin-top: 0;
-    color: rgba(255, 255, 255, 0.87);
+    color: var(--color-text-primary);
   }
 
   p {
-    color: rgba(255, 255, 255, 0.7);
+    color: var(--color-text-secondary);
     line-height: 1.6;
   }
 
   .share-content {
     display: flex;
     flex-direction: column;
-    gap: 1rem;
+    gap: var(--space-lg);
   }
 
   .share-url-container {
@@ -602,33 +609,33 @@
 
   .share-url-input {
     width: 100%;
-    padding: 0.75rem;
-    background-color: #2a2a2a;
-    border: 1px solid #3a3a3a;
-    color: rgba(255, 255, 255, 0.87);
-    font-size: 0.875rem;
+    padding: var(--space-md);
+    background-color: var(--color-surface-3);
+    border: 1px solid var(--color-border-default);
+    color: var(--color-text-primary);
+    font-size: var(--font-base);
     font-family: monospace;
     outline: none;
     box-sizing: border-box;
   }
 
   .share-url-input:focus {
-    border-color: #646cff;
+    border-color: var(--color-accent-primary);
   }
 
   .share-instructions {
-    font-size: 0.875rem;
-    color: rgba(255, 255, 255, 0.5);
+    font-size: var(--font-base);
+    color: var(--color-text-tertiary);
     margin: 0;
   }
 
   .audio-permission-content {
     display: flex;
     flex-direction: column;
-    gap: 1rem;
+    gap: var(--space-lg);
     align-items: center;
     text-align: center;
-    padding: 1rem;
+    padding: var(--space-lg);
   }
 
   .audio-permission-content h3 {
@@ -642,15 +649,15 @@
   }
 
   .enable-audio-button {
-    margin-top: 1rem;
-    padding: 0.75rem 2rem;
-    background-color: #646cff;
+    margin-top: var(--space-lg);
+    padding: var(--space-md) var(--space-2xl);
+    background-color: var(--color-accent-primary);
     color: white;
     border: none;
-    font-size: 1rem;
+    font-size: var(--font-lg);
     font-weight: 600;
     cursor: pointer;
-    transition: background-color 0.2s;
+    transition: background-color var(--transition-base);
   }
 
   .enable-audio-button:hover {
@@ -658,6 +665,6 @@
   }
 
   .enable-audio-button:active {
-    background-color: #424ab8;
+    background-color: var(--color-accent-primary-active);
   }
 </style>
diff --git a/src/lib/components/editor/Editor.svelte b/src/lib/components/editor/Editor.svelte
index 509d7ce..90b48a3 100644
--- a/src/lib/components/editor/Editor.svelte
+++ b/src/lib/components/editor/Editor.svelte
@@ -6,10 +6,9 @@
   import { defaultKeymap, history, historyKeymap } from '@codemirror/commands';
   import { searchKeymap, highlightSelectionMatches } from '@codemirror/search';
   import { autocompletion, completionKeymap, closeBrackets, closeBracketsKeymap } from '@codemirror/autocomplete';
-  import { foldGutter, indentOnInput, syntaxHighlighting, defaultHighlightStyle, bracketMatching, foldKeymap } from '@codemirror/language';
+  import { foldGutter, indentOnInput, bracketMatching, foldKeymap } from '@codemirror/language';
   import { lintKeymap } from '@codemirror/lint';
   import { csoundMode } from '@hlolli/codemirror-lang-csound';
-  import { oneDark } from '@codemirror/theme-one-dark';
   import { vim } from '@replit/codemirror-vim';
   import type { EditorSettingsStore } from '../../stores/editorSettings';
   import {
@@ -20,6 +19,7 @@
     getDocument
   } from '../../editor/block-eval';
   import { csoundTooltip, csoundTooltipTheme } from '../../csound-reference/csoundTooltips';
+  import { createCodeMirrorTheme } from '../../editor/codemirror-theme';
 
   interface Props {
     value: string;
@@ -44,6 +44,8 @@
   const lineWrappingCompartment = new Compartment();
   const vimCompartment = new Compartment();
   const languageCompartment = new Compartment();
+  const hoverTooltipCompartment = new Compartment();
+  const themeCompartment = new Compartment();
 
   function handleExecute() {
     if (!editorView) return;
@@ -93,14 +95,12 @@
       drawSelection(),
       dropCursor(),
       indentOnInput(),
-      syntaxHighlighting(defaultHighlightStyle, { fallback: true }),
       bracketMatching(),
       closeBrackets(),
       autocompletion(),
       rectangularSelection(),
       crosshairCursor(),
       highlightSelectionMatches(),
-      csoundTooltip,
       csoundTooltipTheme,
       keymap.of([
         ...closeBracketsKeymap,
@@ -122,12 +122,13 @@
       extensions: [
         ...baseExtensions,
         languageCompartment.of(csoundMode({ fileType })),
-        oneDark,
+        themeCompartment.of(createCodeMirrorTheme()),
         evaluateKeymap,
         flashField(),
         lineNumbersCompartment.of(initSettings.showLineNumbers ? lineNumbers() : []),
         lineWrappingCompartment.of(initSettings.enableLineWrapping ? EditorView.lineWrapping : []),
         vimCompartment.of(initSettings.vimMode ? vim() : []),
+        hoverTooltipCompartment.of(initSettings.enableHoverTooltips ? csoundTooltip : []),
         EditorView.updateListener.of((update) => {
           if (update.docChanged && onChange) {
             onChange(update.state.doc.toString());
@@ -152,7 +153,8 @@
       effects: [
         lineNumbersCompartment.reconfigure(settings.showLineNumbers ? lineNumbers() : []),
         lineWrappingCompartment.reconfigure(settings.enableLineWrapping ? EditorView.lineWrapping : []),
-        vimCompartment.reconfigure(settings.vimMode ? vim() : [])
+        vimCompartment.reconfigure(settings.vimMode ? vim() : []),
+        hoverTooltipCompartment.reconfigure(settings.enableHoverTooltips ? csoundTooltip : [])
       ]
     });
 
@@ -160,6 +162,20 @@
     editorView.dom.style.fontFamily = settings.fontFamily;
   });
 
+  $effect(() => {
+    const theme = $editorSettings.theme;
+    if (!editorView) return;
+
+    // Wait for CSS variables to be recomputed after theme change
+    requestAnimationFrame(() => {
+      if (editorView) {
+        editorView.dispatch({
+          effects: themeCompartment.reconfigure(createCodeMirrorTheme())
+        });
+      }
+    });
+  });
+
   $effect(() => {
     if (!editorView) return;
 
diff --git a/src/lib/components/editor/EditorSettings.svelte b/src/lib/components/editor/EditorSettings.svelte
index fcc2d80..d775223 100644
--- a/src/lib/components/editor/EditorSettings.svelte
+++ b/src/lib/components/editor/EditorSettings.svelte
@@ -15,6 +15,26 @@
 </script>
 
 <div class="editor-settings">
+  <div class="setting">
+    <span class="label-text">Theme</span>
+    <div class="theme-toggle">
+      <button
+        class="theme-option"
+        class:active={settings.theme === 'dark'}
+        onclick={() => updateSetting('theme', 'dark')}
+      >
+        Dark
+      </button>
+      <button
+        class="theme-option"
+        class:active={settings.theme === 'light'}
+        onclick={() => updateSetting('theme', 'light')}
+      >
+        Light
+      </button>
+    </div>
+  </div>
+
   <div class="setting">
     <label>
       <span class="label-text">Font Size: {settings.fontSize}px</span>
@@ -87,17 +107,26 @@
       />
       <span>Enable line wrapping</span>
     </label>
+
+    <label class="checkbox-label">
+      <input
+        type="checkbox"
+        checked={settings.enableHoverTooltips}
+        onchange={(e) => updateSetting('enableHoverTooltips', e.currentTarget.checked)}
+      />
+      <span>Enable hover tooltips</span>
+    </label>
   </div>
 </div>
 
 <style>
   .editor-settings {
-    padding: 0.5rem;
-    color: rgba(255, 255, 255, 0.87);
+    padding: var(--space-sm);
+    color: var(--color-text-primary);
   }
 
   .setting {
-    margin-bottom: 1rem;
+    margin-bottom: var(--space-lg);
   }
 
   label {
@@ -106,10 +135,44 @@
 
   .label-text {
     display: block;
-    font-size: 0.75rem;
+    font-size: var(--font-sm);
     font-weight: 500;
-    color: rgba(255, 255, 255, 0.6);
-    margin-bottom: 0.25rem;
+    color: var(--color-text-secondary);
+    margin-bottom: var(--space-xs);
+  }
+
+  .theme-toggle {
+    display: flex;
+    gap: 0;
+    border: 1px solid var(--color-border-default);
+    overflow: hidden;
+  }
+
+  .theme-option {
+    flex: 1;
+    padding: var(--space-sm) var(--space-lg);
+    background-color: transparent;
+    color: var(--color-text-secondary);
+    border: none;
+    cursor: pointer;
+    font-size: var(--font-sm);
+    font-weight: 500;
+    transition: all var(--transition-base);
+    border-right: 1px solid var(--color-border-default);
+  }
+
+  .theme-option:last-child {
+    border-right: none;
+  }
+
+  .theme-option:hover:not(.active) {
+    background-color: var(--color-hover-overlay);
+    color: var(--color-text-primary);
+  }
+
+  .theme-option.active {
+    background-color: var(--color-accent-primary);
+    color: white;
   }
 
   input[type="range"] {
@@ -124,14 +187,14 @@
     appearance: none;
     width: 12px;
     height: 12px;
-    background: #646cff;
+    background: var(--color-accent-primary);
     cursor: pointer;
   }
 
   input[type="range"]::-moz-range-thumb {
     width: 12px;
     height: 12px;
-    background: #646cff;
+    background: var(--color-accent-primary);
     cursor: pointer;
     border: none;
   }
@@ -141,45 +204,45 @@
   }
 
   input[type="range"]::-webkit-slider-thumb:hover {
-    background: #818cf8;
+    background: var(--color-accent-primary-hover);
   }
 
   input[type="range"]::-moz-range-thumb:hover {
-    background: #818cf8;
+    background: var(--color-accent-primary-hover);
   }
 
   select {
     width: 100%;
-    background-color: #1a1a1a;
-    color: rgba(255, 255, 255, 0.87);
+    background-color: var(--color-bg-base);
+    color: var(--color-text-primary);
     border: 1px solid #555;
     padding: 0.4rem;
-    font-size: 0.75rem;
+    font-size: var(--font-sm);
     cursor: pointer;
   }
 
   select:hover {
-    border-color: #646cff;
+    border-color: var(--color-accent-primary);
   }
 
   select:focus {
     outline: none;
-    border-color: #646cff;
+    border-color: var(--color-accent-primary);
   }
 
   .checkboxes {
     display: flex;
     flex-direction: column;
-    gap: 0.5rem;
+    gap: var(--space-sm);
   }
 
   .checkbox-label {
     display: flex;
     align-items: center;
-    gap: 0.5rem;
-    font-size: 0.75rem;
+    gap: var(--space-sm);
+    font-size: var(--font-sm);
     font-weight: 500;
-    color: rgba(255, 255, 255, 0.6);
+    color: var(--color-text-secondary);
     cursor: pointer;
   }
 
@@ -190,7 +253,7 @@
     background-color: #4b5563;
     border: 1px solid #6b7280;
     cursor: pointer;
-    transition: all 0.2s;
+    transition: all var(--transition-base);
   }
 
   input[type="checkbox"]:hover {
@@ -199,13 +262,13 @@
   }
 
   input[type="checkbox"]:checked {
-    background-color: #646cff;
-    border-color: #646cff;
+    background-color: var(--color-accent-primary);
+    border-color: var(--color-accent-primary);
   }
 
   input[type="checkbox"]:checked:hover {
-    background-color: #818cf8;
-    border-color: #818cf8;
+    background-color: var(--color-accent-primary-hover);
+    border-color: var(--color-accent-primary-hover);
   }
 
   input[type="checkbox"]:checked::before {
diff --git a/src/lib/components/editor/EditorWithLogs.svelte b/src/lib/components/editor/EditorWithLogs.svelte
index 76c29f9..cc3298f 100644
--- a/src/lib/components/editor/EditorWithLogs.svelte
+++ b/src/lib/components/editor/EditorWithLogs.svelte
@@ -113,15 +113,15 @@
 
   .resize-divider {
     height: 4px;
-    background-color: #2a2a2a;
+    background-color: var(--color-surface-3);
     cursor: ns-resize;
-    transition: background-color 0.2s;
+    transition: background-color var(--transition-base);
     z-index: 10;
   }
 
   .resize-divider:hover,
   .resize-divider:active {
-    background-color: #646cff;
+    background-color: var(--color-accent-primary);
   }
 
   .logs-section {
diff --git a/src/lib/components/editor/LogPanel.svelte b/src/lib/components/editor/LogPanel.svelte
index 5c070b5..2115677 100644
--- a/src/lib/components/editor/LogPanel.svelte
+++ b/src/lib/components/editor/LogPanel.svelte
@@ -188,86 +188,86 @@
     display: flex;
     flex-direction: column;
     height: 100%;
-    background-color: #1a1a1a;
+    background-color: var(--color-bg-base);
   }
 
   .log-header {
     display: flex;
     justify-content: space-between;
     align-items: center;
-    padding: 0.5rem 0.75rem;
-    background-color: #2a2a2a;
-    border-bottom: 1px solid #3a3a3a;
+    padding: var(--space-sm) var(--space-md);
+    background-color: var(--color-surface-3);
+    border-bottom: 1px solid var(--color-border-default);
     cursor: pointer;
-    transition: background-color 0.2s;
+    transition: background-color var(--transition-base);
   }
 
   .log-header:hover {
-    background-color: #323232;
+    background-color: var(--color-hover-overlay);
   }
 
   .search-bar {
     display: flex;
     align-items: center;
-    gap: 0.5rem;
-    padding: 0.5rem 0.75rem;
-    background-color: #252525;
-    border-bottom: 1px solid #3a3a3a;
+    gap: var(--space-sm);
+    padding: var(--space-sm) var(--space-md);
+    background-color: var(--color-surface-2);
+    border-bottom: 1px solid var(--color-border-default);
   }
 
   .search-bar :global(.search-icon) {
-    color: rgba(255, 255, 255, 0.4);
+    color: var(--color-text-tertiary);
     flex-shrink: 0;
   }
 
   .search-input {
     flex: 1;
-    background-color: #1a1a1a;
-    color: rgba(255, 255, 255, 0.87);
-    border: 1px solid #3a3a3a;
-    padding: 0.375rem 0.5rem;
-    font-size: 0.875rem;
-    font-family: 'Courier New', monospace;
+    background-color: var(--color-bg-base);
+    color: var(--color-text-primary);
+    border: 1px solid var(--color-border-default);
+    padding: 0.375rem var(--space-sm);
+    font-size: var(--font-base);
+    font-family: var(--font-mono);
     outline: none;
-    transition: border-color 0.2s;
+    transition: border-color var(--transition-base);
   }
 
   .search-input:focus {
-    border-color: rgba(255, 255, 255, 0.4);
+    border-color: var(--color-text-tertiary);
   }
 
   .search-input::placeholder {
-    color: rgba(255, 255, 255, 0.3);
+    color: var(--color-text-disabled);
   }
 
   .log-title {
-    font-size: 0.75rem;
+    font-size: var(--font-sm);
     font-weight: 600;
-    color: rgba(255, 255, 255, 0.6);
+    color: var(--color-text-secondary);
     text-transform: uppercase;
     letter-spacing: 0.05em;
   }
 
   .log-actions {
     display: flex;
-    gap: 0.25rem;
+    gap: var(--space-xs);
   }
 
   .action-button {
-    padding: 0.25rem;
+    padding: var(--space-xs);
     background-color: transparent;
-    color: rgba(255, 255, 255, 0.6);
+    color: var(--color-text-secondary);
     border: none;
     cursor: pointer;
     display: flex;
     align-items: center;
     justify-content: center;
-    transition: all 0.2s;
+    transition: all var(--transition-base);
   }
 
   .action-button:hover:not(:disabled) {
-    color: rgba(255, 255, 255, 0.9);
-    background-color: rgba(255, 255, 255, 0.1);
+    color: var(--color-text-primary);
+    background-color: var(--color-active-overlay);
   }
 
   .action-button:disabled {
@@ -298,27 +298,27 @@
   .log-content {
     flex: 1;
     overflow-y: auto;
-    padding: 0.5rem;
-    font-family: 'Courier New', monospace;
-    font-size: 0.875rem;
+    padding: var(--space-sm);
+    font-family: var(--font-mono);
+    font-size: var(--font-base);
   }
 
   .empty-state {
-    color: rgba(255, 255, 255, 0.4);
+    color: var(--color-text-tertiary);
     text-align: center;
-    padding: 2rem;
+    padding: var(--space-2xl);
   }
 
   .log-entry {
     display: flex;
-    gap: 0.75rem;
-    padding: 0.25rem 0.5rem;
-    color: rgba(255, 255, 255, 0.87);
-    border-bottom: 1px solid #2a2a2a;
+    gap: var(--space-md);
+    padding: var(--space-xs) var(--space-sm);
+    color: var(--color-text-primary);
+    border-bottom: 1px solid var(--color-surface-3);
   }
 
   .log-entry:hover {
-    background-color: #252525;
+    background-color: var(--color-surface-2);
   }
 
   .log-entry.error {
@@ -331,9 +331,9 @@
   }
 
   .log-timestamp {
-    color: rgba(255, 255, 255, 0.4);
+    color: var(--color-text-tertiary);
     min-width: 6rem;
-    font-size: 0.75rem;
+    font-size: var(--font-sm);
   }
 
   .log-message {
diff --git a/src/lib/components/reference/CsoundReference.svelte b/src/lib/components/reference/CsoundReference.svelte
index 7aeb2e2..a2dafdc 100644
--- a/src/lib/components/reference/CsoundReference.svelte
+++ b/src/lib/components/reference/CsoundReference.svelte
@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { Search, ChevronDown, ChevronRight } from 'lucide-svelte';
+  import { Search, ChevronDown, ChevronRight, ChevronsDown } from 'lucide-svelte';
   import { allCsoundReferences, getCsoundReferencesByCategory } from '../../csound-reference/csoundReference';
   import type { CsoundReference } from '../../csound-reference/types';
   import Fuse from 'fuse.js';
@@ -57,6 +57,10 @@
     expandedCategories = newSet;
   }
 
+  function collapseAll() {
+    expandedCategories = new Set();
+  }
+
   $effect(() => {
     if (searchTerm.trim() && filteredCategories().length > 0 && filteredCategories().length <= 3) {
       expandedCategories = new Set(filteredCategories());
@@ -75,6 +79,15 @@
       bind:value={searchTerm}
       class="search-input"
     />
+    {#if expandedCategories.size > 0}
+      <button
+        class="collapse-button"
+        onclick={collapseAll}
+        title="Collapse all categories"
+      >
+        <ChevronsDown size={16} />
+      </button>
+    {/if}
   </div>
 
   <div class="reference-content">
@@ -117,22 +130,15 @@
                       <div class="params-label">
                         Parameters ({opcode.parameters.length}):
                       </div>
-                      {#each opcode.parameters.slice(0, 5) as param}
+                      {#each opcode.parameters as param}
                         <div class="param">
-                          <span class="param-name">{param.name}</span>
-                          <span class="param-type">({param.type})</span>
-                          <span class="param-desc">
-                            {param.description.length > 80
-                              ? param.description.substring(0, 80) + '...'
-                              : param.description}
-                          </span>
+                          <div class="param-header">
+                            <span class="param-name">{param.name}</span>
+                            <span class="param-type">{param.type}</span>
+                          </div>
+                          <div class="param-desc">{param.description}</div>
                         </div>
                       {/each}
-                      {#if opcode.parameters.length > 5}
-                        <div class="param-more">
-                          ... and {opcode.parameters.length - 5} more
-                        </div>
-                      {/if}
                     </div>
                   {/if}
                 </div>
@@ -164,67 +170,91 @@
   .search-bar {
     display: flex;
     align-items: center;
-    gap: 0.5rem;
-    padding: 0.75rem;
-    background-color: #252525;
-    border-bottom: 1px solid #3a3a3a;
+    gap: var(--space-sm);
+    padding: var(--space-md);
+    background-color: var(--color-surface-2);
+    border-bottom: 1px solid var(--color-border-subtle);
   }
 
   .search-bar :global(.search-icon) {
-    color: rgba(255, 255, 255, 0.4);
+    color: var(--color-text-tertiary);
     flex-shrink: 0;
   }
 
   .search-input {
     flex: 1;
-    background-color: #1a1a1a;
-    color: rgba(255, 255, 255, 0.87);
-    border: 1px solid #3a3a3a;
-    padding: 0.5rem;
-    font-size: 0.875rem;
-    font-family: 'Courier New', monospace;
+    background-color: var(--input-bg);
+    color: var(--color-text-primary);
+    border: 1px solid var(--input-border);
+    padding: var(--space-sm);
+    font-size: var(--font-base);
+    font-family: var(--font-mono);
     outline: none;
-    transition: border-color 0.2s;
+    transition: border-color var(--transition-base);
   }
 
   .search-input:focus {
-    border-color: #646cff;
+    border-color: var(--input-border-focus);
   }
 
   .search-input::placeholder {
-    color: rgba(255, 255, 255, 0.3);
+    color: var(--color-text-disabled);
+  }
+
+  .collapse-button {
+    padding: var(--space-sm);
+    background-color: transparent;
+    color: var(--color-text-secondary);
+    border: 1px solid var(--color-border-default);
+    cursor: pointer;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    transition: all var(--transition-base);
+    flex-shrink: 0;
+  }
+
+  .collapse-button:hover {
+    color: var(--color-text-primary);
+    background-color: var(--color-hover-overlay);
+    border-color: var(--color-border-strong);
   }
 
   .reference-content {
     flex: 1;
     overflow-y: auto;
-    padding: 0.5rem;
+    padding: 0;
   }
 
   .category {
-    margin-bottom: 0.75rem;
+    margin-bottom: 0;
+    border-bottom: 1px solid var(--accordion-border);
+  }
+
+  .category:last-child {
+    border-bottom: none;
   }
 
   .category-header {
     display: flex;
     align-items: center;
-    gap: 0.5rem;
+    gap: var(--space-sm);
     width: 100%;
-    padding: 0.5rem;
-    background-color: #2a2a2a;
+    padding: var(--space-md) var(--space-lg);
+    background-color: var(--accordion-header-bg);
     border: none;
-    color: rgba(255, 255, 255, 0.87);
+    color: var(--color-text-primary);
     cursor: pointer;
-    transition: background-color 0.2s;
-    font-size: 0.875rem;
+    transition: background-color var(--transition-base);
+    font-size: var(--font-base);
   }
 
   .category-header:hover {
-    background-color: #323232;
+    background-color: var(--accordion-header-hover);
   }
 
   .category-header :global(svg) {
-    color: rgba(255, 255, 255, 0.6);
+    color: var(--color-text-tertiary);
     flex-shrink: 0;
   }
 
@@ -235,112 +265,117 @@
   }
 
   .category-count {
-    font-size: 0.75rem;
-    color: rgba(255, 255, 255, 0.5);
-    background-color: #646cff;
-    padding: 0.125rem 0.5rem;
+    font-size: var(--font-xs);
+    color: var(--color-text-primary);
+    background-color: var(--color-accent-primary-subtle);
+    padding: 2px var(--space-sm);
+    border-radius: var(--radius-sm);
   }
 
   .opcodes {
-    padding-left: 1.5rem;
-    margin-top: 0.5rem;
+    padding: var(--space-lg);
   }
 
   .opcode {
-    background-color: #1a1a1a;
-    padding: 0.75rem;
-    margin-bottom: 0.5rem;
-    border-left: 2px solid #646cff;
+    background-color: transparent;
+    padding: var(--space-lg) 0;
+    margin-bottom: 0;
+    border-bottom: 1px solid var(--color-border-subtle);
+  }
+
+  .opcode:last-child {
+    border-bottom: none;
   }
 
   .opcode-header {
     display: flex;
     align-items: center;
-    gap: 0.5rem;
-    margin-bottom: 0.5rem;
+    gap: var(--space-sm);
+    margin-bottom: var(--space-sm);
   }
 
   .opcode-name {
-    font-family: 'Courier New', monospace;
-    font-size: 0.875rem;
+    font-family: var(--font-mono);
+    font-size: var(--font-base);
     font-weight: 600;
-    color: #646cff;
+    color: var(--color-accent-primary);
   }
 
   .opcode-type {
-    font-size: 0.75rem;
-    color: rgba(255, 255, 255, 0.5);
-    text-transform: uppercase;
+    font-size: var(--font-xs);
+    color: var(--color-text-tertiary);
+    text-transform: lowercase;
   }
 
   .opcode-description {
-    color: rgba(255, 255, 255, 0.87);
-    font-size: 0.8125rem;
-    line-height: 1.5;
-    margin: 0 0 0.5rem 0;
+    color: var(--color-text-secondary);
+    font-size: var(--font-md);
+    line-height: var(--leading-relaxed);
+    margin: 0 0 var(--space-md) 0;
   }
 
   .opcode-syntax {
-    background-color: #000;
-    color: #fbbf24;
-    padding: 0.5rem;
-    font-size: 0.75rem;
-    font-family: 'Courier New', monospace;
-    margin: 0 0 0.5rem 0;
+    background-color: var(--color-surface-2);
+    color: var(--color-text-primary);
+    padding: var(--space-md);
+    font-size: var(--font-sm);
+    font-family: var(--font-mono);
+    margin: 0 0 var(--space-md) 0;
     overflow-x: auto;
-    white-space: pre-wrap;
-    word-break: break-all;
-    border: 1px solid #2a2a2a;
+    white-space: pre;
+    border: 1px solid var(--color-border-subtle);
+    line-height: var(--leading-normal);
   }
 
   .opcode-rates {
-    font-size: 0.75rem;
-    color: #60a5fa;
-    margin-bottom: 0.5rem;
+    font-size: var(--font-sm);
+    color: var(--color-info);
+    margin-bottom: var(--space-md);
   }
 
   .opcode-params {
-    margin-top: 0.5rem;
+    margin-top: var(--space-md);
   }
 
   .params-label {
-    font-size: 0.75rem;
-    color: rgba(255, 255, 255, 0.6);
-    margin-bottom: 0.375rem;
-    text-transform: uppercase;
+    font-size: var(--font-xs);
+    color: var(--color-text-tertiary);
+    margin-bottom: var(--space-sm);
+    text-transform: lowercase;
     font-weight: 500;
   }
 
   .param {
     display: flex;
-    gap: 0.375rem;
-    font-size: 0.75rem;
-    line-height: 1.4;
-    margin-bottom: 0.25rem;
+    flex-direction: column;
+    gap: var(--space-xs);
+    font-size: var(--font-sm);
+    line-height: var(--leading-normal);
+    margin-bottom: var(--space-md);
+  }
+
+  .param-header {
+    display: flex;
+    align-items: center;
+    gap: var(--space-sm);
   }
 
   .param-name {
-    color: #10b981;
-    font-family: 'Courier New', monospace;
+    color: var(--color-text-primary);
+    font-family: var(--font-mono);
     font-weight: 500;
-    min-width: 4rem;
+    font-size: var(--font-sm);
   }
 
   .param-type {
-    color: rgba(255, 255, 255, 0.4);
-    font-size: 0.6875rem;
+    color: var(--color-text-tertiary);
+    font-size: var(--font-xs);
   }
 
   .param-desc {
-    color: rgba(255, 255, 255, 0.7);
-    flex: 1;
-  }
-
-  .param-more {
-    font-size: 0.6875rem;
-    color: rgba(255, 255, 255, 0.5);
-    font-style: italic;
-    margin-top: 0.25rem;
+    color: var(--color-text-secondary);
+    font-size: var(--font-sm);
+    line-height: var(--leading-normal);
   }
 
   .empty-state {
@@ -348,26 +383,26 @@
     flex-direction: column;
     align-items: center;
     justify-content: center;
-    padding: 3rem 1rem;
+    padding: var(--space-2xl) var(--space-lg);
     text-align: center;
-    color: rgba(255, 255, 255, 0.5);
+    color: var(--color-text-tertiary);
   }
 
   .empty-state :global(svg) {
-    margin-bottom: 1rem;
+    margin-bottom: var(--space-lg);
     opacity: 0.3;
   }
 
   .empty-state h3 {
-    font-size: 1rem;
+    font-size: var(--font-lg);
     font-weight: 500;
-    margin: 0 0 0.5rem 0;
-    color: rgba(255, 255, 255, 0.6);
+    margin: 0 0 var(--space-sm) 0;
+    color: var(--color-text-secondary);
   }
 
   .empty-state p {
-    font-size: 0.875rem;
+    font-size: var(--font-base);
     margin: 0;
-    color: rgba(255, 255, 255, 0.4);
+    color: var(--color-text-tertiary);
   }
 </style>
diff --git a/src/lib/components/ui/ConfirmDialog.svelte b/src/lib/components/ui/ConfirmDialog.svelte
index 4418fc8..3fdf3f9 100644
--- a/src/lib/components/ui/ConfirmDialog.svelte
+++ b/src/lib/components/ui/ConfirmDialog.svelte
@@ -48,42 +48,42 @@
 
 <style>
   .confirm-dialog p {
-    margin: 0 0 1.5rem 0;
-    color: rgba(255, 255, 255, 0.87);
+    margin: 0 0 var(--space-xl) 0;
+    color: var(--color-text-primary);
     line-height: 1.5;
   }
 
   .button-group {
     display: flex;
-    gap: 0.75rem;
+    gap: var(--space-md);
     justify-content: flex-end;
   }
 
   .button {
-    padding: 0.5rem 1rem;
+    padding: var(--space-sm) var(--space-lg);
     border: none;
     cursor: pointer;
-    font-size: 0.875rem;
-    transition: all 0.2s;
+    font-size: var(--font-base);
+    transition: all var(--transition-base);
   }
 
   .button-primary {
-    background-color: #646cff;
+    background-color: var(--color-accent-primary);
     color: white;
   }
 
   .button-primary:hover {
-    background-color: #535bf2;
+    background-color: var(--color-accent-primary-active);
   }
 
   .button-secondary {
     background-color: transparent;
-    color: rgba(255, 255, 255, 0.6);
-    border: 1px solid #3a3a3a;
+    color: var(--color-text-secondary);
+    border: 1px solid var(--color-border-default);
   }
 
   .button-secondary:hover {
-    background-color: rgba(255, 255, 255, 0.05);
-    color: rgba(255, 255, 255, 0.87);
+    background-color: var(--color-hover-overlay);
+    color: var(--color-text-primary);
   }
 </style>
diff --git a/src/lib/components/ui/FileBrowser.svelte b/src/lib/components/ui/FileBrowser.svelte
index fe615eb..dcff52d 100644
--- a/src/lib/components/ui/FileBrowser.svelte
+++ b/src/lib/components/ui/FileBrowser.svelte
@@ -235,46 +235,46 @@
     display: flex;
     flex-direction: column;
     height: 100%;
-    background-color: #1a1a1a;
+    background-color: var(--color-bg-base);
   }
 
   .browser-header {
     display: flex;
     justify-content: space-between;
     align-items: center;
-    padding: 0.75rem;
-    background-color: #2a2a2a;
-    border-bottom: 1px solid #3a3a3a;
+    padding: var(--space-md);
+    background-color: var(--color-surface-3);
+    border-bottom: 1px solid var(--color-border-default);
   }
 
   .browser-title {
-    font-size: 0.75rem;
+    font-size: var(--font-sm);
     font-weight: 600;
-    color: rgba(255, 255, 255, 0.6);
+    color: var(--color-text-secondary);
     text-transform: uppercase;
     letter-spacing: 0.05em;
   }
 
   .header-actions {
     display: flex;
-    gap: 0.25rem;
+    gap: var(--space-xs);
   }
 
   .action-button {
     padding: 0.375rem;
     background-color: transparent;
-    color: rgba(255, 255, 255, 0.7);
+    color: var(--color-text-secondary);
     border: none;
     cursor: pointer;
     display: flex;
     align-items: center;
     justify-content: center;
-    transition: all 0.2s;
+    transition: all var(--transition-base);
   }
 
   .action-button:hover {
-    color: rgba(255, 255, 255, 1);
-    background-color: rgba(255, 255, 255, 0.1);
+    color: var(--color-text-primary);
+    background-color: var(--color-active-overlay);
   }
 
   .browser-content {
@@ -283,9 +283,9 @@
   }
 
   .empty-state {
-    padding: 2rem 1rem;
+    padding: var(--space-2xl) var(--space-lg);
     text-align: center;
-    color: rgba(255, 255, 255, 0.4);
+    color: var(--color-text-tertiary);
   }
 
   .project-list {
@@ -296,24 +296,24 @@
   .project-item {
     display: flex;
     align-items: center;
-    gap: 0.75rem;
-    padding: 0.75rem;
-    border-bottom: 1px solid #2a2a2a;
+    gap: var(--space-md);
+    padding: var(--space-md);
+    border-bottom: 1px solid var(--color-surface-3);
     cursor: pointer;
-    transition: background-color 0.2s;
+    transition: background-color var(--transition-base);
   }
 
   .project-item:hover {
-    background-color: #252525;
+    background-color: var(--color-surface-2);
   }
 
   .project-item.selected {
     background-color: rgba(100, 108, 255, 0.2);
-    border-left: 3px solid #646cff;
+    border-left: 3px solid var(--color-accent-primary);
   }
 
   .project-icon {
-    color: rgba(255, 255, 255, 0.6);
+    color: var(--color-text-secondary);
     display: flex;
     align-items: center;
   }
@@ -324,24 +324,24 @@
   }
 
   .project-title {
-    font-size: 0.875rem;
-    color: rgba(255, 255, 255, 0.87);
+    font-size: var(--font-base);
+    color: var(--color-text-primary);
     white-space: nowrap;
     overflow: hidden;
     text-overflow: ellipsis;
   }
 
   .delete-button {
-    padding: 0.25rem;
+    padding: var(--space-xs);
     background-color: transparent;
-    color: rgba(255, 255, 255, 0.4);
+    color: var(--color-text-tertiary);
     border: none;
     cursor: pointer;
     display: flex;
     align-items: center;
     justify-content: center;
     opacity: 0;
-    transition: all 0.2s;
+    transition: all var(--transition-base);
   }
 
   .project-item:hover .delete-button {
@@ -354,50 +354,50 @@
   }
 
   .metadata-editor {
-    border-top: 1px solid #2a2a2a;
-    background-color: #1a1a1a;
-    padding: 1rem;
+    border-top: 1px solid var(--color-surface-3);
+    background-color: var(--color-bg-base);
+    padding: var(--space-lg);
   }
 
   .metadata-header {
-    font-size: 0.75rem;
+    font-size: var(--font-sm);
     font-weight: 600;
-    color: rgba(255, 255, 255, 0.6);
+    color: var(--color-text-secondary);
     text-transform: uppercase;
     letter-spacing: 0.05em;
-    margin-bottom: 1rem;
+    margin-bottom: var(--space-lg);
   }
 
   .metadata-fields {
     display: flex;
     flex-direction: column;
-    gap: 0.75rem;
+    gap: var(--space-md);
   }
 
   .field {
     display: flex;
     flex-direction: column;
-    gap: 0.25rem;
+    gap: var(--space-xs);
   }
 
   .field label {
-    font-size: 0.75rem;
-    color: rgba(255, 255, 255, 0.6);
+    font-size: var(--font-sm);
+    color: var(--color-text-secondary);
   }
 
   .field input,
   .field select {
-    padding: 0.5rem;
-    background-color: #2a2a2a;
-    border: 1px solid #3a3a3a;
-    color: rgba(255, 255, 255, 0.87);
-    font-size: 0.875rem;
+    padding: var(--space-sm);
+    background-color: var(--color-surface-3);
+    border: 1px solid var(--color-border-default);
+    color: var(--color-text-primary);
+    font-size: var(--font-base);
     outline: none;
   }
 
   .field input:focus,
   .field select:focus {
-    border-color: #646cff;
+    border-color: var(--color-accent-primary);
   }
 
   .field select {
@@ -405,11 +405,11 @@
   }
 
   .field.readonly .readonly-value {
-    padding: 0.5rem;
-    background-color: #1a1a1a;
-    border: 1px solid #2a2a2a;
-    color: rgba(255, 255, 255, 0.6);
-    font-size: 0.875rem;
+    padding: var(--space-sm);
+    background-color: var(--color-bg-base);
+    border: 1px solid var(--color-surface-3);
+    color: var(--color-text-secondary);
+    font-size: var(--font-base);
     font-family: monospace;
   }
 </style>
diff --git a/src/lib/components/ui/InputDialog.svelte b/src/lib/components/ui/InputDialog.svelte
index b75f800..87eeb76 100644
--- a/src/lib/components/ui/InputDialog.svelte
+++ b/src/lib/components/ui/InputDialog.svelte
@@ -64,58 +64,58 @@
   .input-dialog {
     display: flex;
     flex-direction: column;
-    gap: 1rem;
+    gap: var(--space-lg);
   }
 
   label {
-    color: rgba(255, 255, 255, 0.87);
-    font-size: 0.875rem;
+    color: var(--color-text-primary);
+    font-size: var(--font-base);
   }
 
   input {
-    padding: 0.5rem;
-    background-color: #1a1a1a;
-    border: 1px solid #3a3a3a;
-    color: rgba(255, 255, 255, 0.87);
-    font-size: 0.875rem;
+    padding: var(--space-sm);
+    background-color: var(--color-bg-base);
+    border: 1px solid var(--color-border-default);
+    color: var(--color-text-primary);
+    font-size: var(--font-base);
     outline: none;
   }
 
   input:focus {
-    border-color: #646cff;
+    border-color: var(--color-accent-primary);
   }
 
   .button-group {
     display: flex;
-    gap: 0.75rem;
+    gap: var(--space-md);
     justify-content: flex-end;
   }
 
   .button {
-    padding: 0.5rem 1rem;
+    padding: var(--space-sm) var(--space-lg);
     border: none;
     cursor: pointer;
-    font-size: 0.875rem;
-    transition: all 0.2s;
+    font-size: var(--font-base);
+    transition: all var(--transition-base);
   }
 
   .button-primary {
-    background-color: #646cff;
+    background-color: var(--color-accent-primary);
     color: white;
   }
 
   .button-primary:hover {
-    background-color: #535bf2;
+    background-color: var(--color-accent-primary-active);
   }
 
   .button-secondary {
     background-color: transparent;
-    color: rgba(255, 255, 255, 0.6);
-    border: 1px solid #3a3a3a;
+    color: var(--color-text-secondary);
+    border: 1px solid var(--color-border-default);
   }
 
   .button-secondary:hover {
-    background-color: rgba(255, 255, 255, 0.05);
-    color: rgba(255, 255, 255, 0.87);
+    background-color: var(--color-hover-overlay);
+    color: var(--color-text-primary);
   }
 </style>
diff --git a/src/lib/components/ui/Modal.svelte b/src/lib/components/ui/Modal.svelte
index d04eb27..91c6a3c 100644
--- a/src/lib/components/ui/Modal.svelte
+++ b/src/lib/components/ui/Modal.svelte
@@ -52,8 +52,8 @@
   }
 
   .modal-content {
-    background-color: #2a2a2a;
-    border: 1px solid #3a3a3a;
+    background-color: var(--color-surface-3);
+    border: 1px solid var(--color-border-default);
     min-width: 300px;
     max-width: 500px;
     max-height: 80vh;
@@ -61,18 +61,18 @@
   }
 
   .modal-header {
-    padding: 1rem 1.5rem;
-    border-bottom: 1px solid #3a3a3a;
+    padding: var(--space-lg) var(--space-xl);
+    border-bottom: 1px solid var(--color-border-default);
   }
 
   .modal-header h3 {
     margin: 0;
-    color: rgba(255, 255, 255, 0.87);
-    font-size: 1rem;
+    color: var(--color-text-primary);
+    font-size: var(--font-lg);
     font-weight: 600;
   }
 
   .modal-body {
-    padding: 1.5rem;
+    padding: var(--space-xl);
   }
 </style>
diff --git a/src/lib/components/ui/Popup.svelte b/src/lib/components/ui/Popup.svelte
index 32405eb..f178648 100644
--- a/src/lib/components/ui/Popup.svelte
+++ b/src/lib/components/ui/Popup.svelte
@@ -83,8 +83,8 @@
   .popup {
     position: fixed;
     z-index: 9999;
-    background-color: #1a1a1a;
-    border: 1px solid #333;
+    background-color: var(--color-bg-base);
+    border: 1px solid var(--color-border-default);
     box-shadow: 0 4px 12px rgba(0, 0, 0, 0.5);
     display: flex;
     flex-direction: column;
@@ -94,23 +94,23 @@
     display: flex;
     justify-content: space-between;
     align-items: center;
-    padding: 0.75rem 1rem;
-    background-color: #252525;
-    border-bottom: 1px solid #333;
+    padding: var(--space-md) var(--space-lg);
+    background-color: var(--color-surface-2);
+    border-bottom: 1px solid var(--color-border-default);
     cursor: move;
     user-select: none;
   }
 
   .popup-title {
     font-weight: 600;
-    font-size: 0.875rem;
-    color: rgba(255, 255, 255, 0.87);
+    font-size: var(--font-base);
+    color: var(--color-text-primary);
   }
 
   .close-button {
     background: none;
     border: none;
-    color: rgba(255, 255, 255, 0.6);
+    color: var(--color-text-secondary);
     font-size: 1.5rem;
     line-height: 1;
     padding: 0;
@@ -120,16 +120,16 @@
     display: flex;
     align-items: center;
     justify-content: center;
-    transition: color 0.2s;
+    transition: color var(--transition-base);
   }
 
   .close-button:hover {
-    color: rgba(255, 255, 255, 1);
+    color: var(--color-text-primary);
   }
 
   .popup-content {
     flex: 1;
     overflow: auto;
-    padding: 1rem;
+    padding: var(--space-lg);
   }
 </style>
diff --git a/src/lib/components/ui/ResizablePopup.svelte b/src/lib/components/ui/ResizablePopup.svelte
index de75b98..320ad56 100644
--- a/src/lib/components/ui/ResizablePopup.svelte
+++ b/src/lib/components/ui/ResizablePopup.svelte
@@ -148,8 +148,8 @@
   .resizable-popup {
     position: fixed;
     z-index: 9999;
-    background-color: #1a1a1a;
-    border: 1px solid #333;
+    background-color: var(--color-bg-base);
+    border: 1px solid var(--color-border-default);
     box-shadow: 0 4px 12px rgba(0, 0, 0, 0.5);
     display: flex;
     flex-direction: column;
@@ -159,23 +159,23 @@
     display: flex;
     justify-content: space-between;
     align-items: center;
-    padding: 0.75rem 1rem;
-    background-color: #252525;
-    border-bottom: 1px solid #333;
+    padding: var(--space-md) var(--space-lg);
+    background-color: var(--color-surface-2);
+    border-bottom: 1px solid var(--color-border-default);
     cursor: move;
     user-select: none;
   }
 
   .popup-title {
     font-weight: 600;
-    font-size: 0.875rem;
-    color: rgba(255, 255, 255, 0.87);
+    font-size: var(--font-base);
+    color: var(--color-text-primary);
   }
 
   .close-button {
     background: none;
     border: none;
-    color: rgba(255, 255, 255, 0.6);
+    color: var(--color-text-secondary);
     font-size: 1.5rem;
     line-height: 1;
     padding: 0;
@@ -185,17 +185,17 @@
     display: flex;
     align-items: center;
     justify-content: center;
-    transition: color 0.2s;
+    transition: color var(--transition-base);
   }
 
   .close-button:hover {
-    color: rgba(255, 255, 255, 1);
+    color: var(--color-text-primary);
   }
 
   .popup-content {
     flex: 1;
     overflow: auto;
-    padding: 1rem;
+    padding: var(--space-lg);
   }
 
   .popup-content.no-padding {
diff --git a/src/lib/components/ui/SidePanel.svelte b/src/lib/components/ui/SidePanel.svelte
index b3817ce..47cad50 100644
--- a/src/lib/components/ui/SidePanel.svelte
+++ b/src/lib/components/ui/SidePanel.svelte
@@ -166,7 +166,7 @@
 <style>
   .side-panel {
     position: relative;
-    background-color: #1a1a1a;
+    background-color: var(--color-bg-base);
     display: flex;
     flex-direction: column;
   }
@@ -177,22 +177,22 @@
   }
 
   .side-panel.left {
-    border-right: 1px solid #333;
+    border-right: 1px solid var(--color-border-default);
   }
 
   .side-panel.right {
-    border-left: 1px solid #333;
+    border-left: 1px solid var(--color-border-default);
   }
 
   .side-panel.bottom {
     width: 100%;
-    border-top: 1px solid #333;
+    border-top: 1px solid var(--color-border-default);
   }
 
   .resize-handle {
     position: absolute;
     background-color: transparent;
-    transition: background-color 0.2s;
+    transition: background-color var(--transition-base);
     z-index: 10;
   }
 
@@ -222,75 +222,75 @@
 
   .resize-handle:hover,
   .resize-handle:active {
-    background-color: #646cff;
+    background-color: var(--color-accent-primary);
   }
 
   .tabs {
     display: flex;
     justify-content: space-between;
     align-items: center;
-    border-bottom: 1px solid #333;
-    background-color: #1a1a1a;
+    border-bottom: 1px solid var(--color-border-default);
+    background-color: var(--color-surface-1);
   }
 
   .panel-controls {
     display: flex;
-    gap: 0.25rem;
+    gap: var(--space-xs);
     margin-left: auto;
-    padding-right: 0.5rem;
+    padding-right: var(--space-sm);
   }
 
   .control-button {
-    padding: 0.375rem;
+    padding: var(--space-sm);
     background-color: transparent;
-    color: rgba(255, 255, 255, 0.7);
+    color: var(--color-text-secondary);
     border: none;
     cursor: pointer;
     display: flex;
     align-items: center;
     justify-content: center;
-    transition: all 0.2s;
+    transition: all var(--transition-base);
   }
 
   .control-button:hover {
-    color: rgba(255, 255, 255, 1);
-    background-color: rgba(255, 255, 255, 0.1);
+    color: var(--color-text-primary);
+    background-color: var(--color-hover-overlay);
   }
 
   .panel-header-fallback {
     display: flex;
     justify-content: flex-end;
     align-items: center;
-    border-bottom: 1px solid #333;
-    background-color: #1a1a1a;
-    padding: 0.5rem 0;
+    border-bottom: 1px solid var(--color-border-default);
+    background-color: var(--color-surface-1);
+    padding: var(--space-sm) 0;
   }
 
   .tab {
-    padding: 0.75rem 1rem;
+    padding: var(--space-md) var(--space-lg);
     background: none;
     border: none;
-    color: rgba(255, 255, 255, 0.6);
+    color: var(--color-text-secondary);
     cursor: pointer;
-    font-size: 0.875rem;
+    font-size: var(--font-base);
     font-weight: 500;
     border-bottom: 2px solid transparent;
-    transition: color 0.2s, border-color 0.2s;
+    transition: color var(--transition-base), border-color var(--transition-base);
   }
 
   .tab:hover {
-    color: rgba(255, 255, 255, 0.87);
+    color: var(--color-text-primary);
   }
 
   .tab.active {
-    color: rgba(255, 255, 255, 0.87);
-    border-bottom-color: #646cff;
+    color: var(--color-text-primary);
+    border-bottom-color: var(--color-accent-primary);
   }
 
   .side-panel-content {
     flex: 1;
     overflow: auto;
-    padding: 1rem;
+    padding: 0;
   }
 
   .tab-content {
diff --git a/src/lib/components/ui/TemplateDialog.svelte b/src/lib/components/ui/TemplateDialog.svelte
index 90651d9..c5a14bf 100644
--- a/src/lib/components/ui/TemplateDialog.svelte
+++ b/src/lib/components/ui/TemplateDialog.svelte
@@ -59,8 +59,8 @@
   }
 
   .modal-content {
-    background-color: #1a1a1a;
-    border: 1px solid #3a3a3a;
+    background-color: var(--color-bg-base);
+    border: 1px solid var(--color-border-default);
     width: 400px;
     max-height: 80vh;
     display: flex;
@@ -71,22 +71,22 @@
     display: flex;
     justify-content: space-between;
     align-items: center;
-    padding: 1rem;
-    border-bottom: 1px solid #3a3a3a;
+    padding: var(--space-lg);
+    border-bottom: 1px solid var(--color-border-default);
   }
 
   h2 {
     margin: 0;
-    font-size: 1rem;
+    font-size: var(--font-lg);
     font-weight: 600;
-    color: rgba(255, 255, 255, 0.9);
+    color: var(--color-text-primary);
   }
 
   .close-button {
     background: none;
     border: none;
     font-size: 2rem;
-    color: rgba(255, 255, 255, 0.5);
+    color: var(--color-text-secondary);
     cursor: pointer;
     padding: 0;
     width: 2rem;
@@ -94,12 +94,12 @@
     display: flex;
     align-items: center;
     justify-content: center;
-    transition: color 0.2s;
+    transition: color var(--transition-base);
     line-height: 1;
   }
 
   .close-button:hover {
-    color: rgba(255, 255, 255, 0.9);
+    color: var(--color-text-primary);
   }
 
   .template-list {
@@ -108,19 +108,19 @@
   }
 
   .template-item {
-    padding: 1rem;
+    padding: var(--space-lg);
     background-color: transparent;
     border: none;
-    border-bottom: 1px solid #2a2a2a;
-    color: rgba(255, 255, 255, 0.87);
+    border-bottom: 1px solid var(--color-surface-3);
+    color: var(--color-text-primary);
     text-align: left;
     cursor: pointer;
-    transition: background-color 0.2s;
-    font-size: 0.875rem;
+    transition: background-color var(--transition-base);
+    font-size: var(--font-base);
   }
 
   .template-item:hover {
-    background-color: #2a2a2a;
+    background-color: var(--color-surface-3);
   }
 
   .template-item:last-child {
diff --git a/src/lib/components/ui/TopBar.svelte b/src/lib/components/ui/TopBar.svelte
index 0b4f846..7274b97 100644
--- a/src/lib/components/ui/TopBar.svelte
+++ b/src/lib/components/ui/TopBar.svelte
@@ -28,9 +28,9 @@
     display: flex;
     justify-content: space-between;
     align-items: center;
-    padding: 0.75rem 1rem;
-    background-color: #1a1a1a;
-    border-bottom: 1px solid #333;
+    padding: var(--space-md) var(--space-lg);
+    background-color: var(--color-bg-base);
+    border-bottom: 1px solid var(--color-border-default);
     height: 48px;
     box-sizing: border-box;
   }
@@ -38,24 +38,24 @@
   .left-section {
     display: flex;
     align-items: center;
-    gap: 0.5rem;
+    gap: var(--space-sm);
   }
 
   .title-section {
     display: flex;
     align-items: center;
-    gap: 0.5rem;
-    color: rgba(255, 255, 255, 0.87);
+    gap: var(--space-sm);
+    color: var(--color-text-primary);
   }
 
   .title {
     font-weight: 600;
-    font-size: 1rem;
+    font-size: var(--font-lg);
   }
 
   .actions {
     display: flex;
-    gap: 0.5rem;
+    gap: var(--space-sm);
     align-items: center;
   }
 </style>
diff --git a/src/lib/csound-reference/csoundTooltips.ts b/src/lib/csound-reference/csoundTooltips.ts
index 8a0bb8a..717945c 100644
--- a/src/lib/csound-reference/csoundTooltips.ts
+++ b/src/lib/csound-reference/csoundTooltips.ts
@@ -90,32 +90,33 @@ export const csoundTooltip = hoverTooltip((view, pos) => {
         const paramsList = document.createElement('div');
         paramsList.className = 'csound-tooltip-params';
 
-        reference.parameters.slice(0, 5).forEach(param => {
+        reference.parameters.forEach(param => {
           const paramItem = document.createElement('div');
           paramItem.className = 'csound-tooltip-param';
 
+          const paramHeader = document.createElement('div');
+          paramHeader.className = 'csound-tooltip-param-header';
+
           const paramName = document.createElement('span');
           paramName.className = 'csound-tooltip-param-name';
           paramName.textContent = param.name;
 
-          const paramDesc = document.createElement('span');
-          paramDesc.className = 'csound-tooltip-param-desc';
-          paramDesc.textContent = param.description.length > 60
-            ? param.description.substring(0, 60) + '...'
-            : param.description;
+          const paramType = document.createElement('span');
+          paramType.className = 'csound-tooltip-param-type';
+          paramType.textContent = param.type;
 
-          paramItem.appendChild(paramName);
+          paramHeader.appendChild(paramName);
+          paramHeader.appendChild(paramType);
+
+          const paramDesc = document.createElement('div');
+          paramDesc.className = 'csound-tooltip-param-desc';
+          paramDesc.textContent = param.description;
+
+          paramItem.appendChild(paramHeader);
           paramItem.appendChild(paramDesc);
           paramsList.appendChild(paramItem);
         });
 
-        if (reference.parameters.length > 5) {
-          const more = document.createElement('div');
-          more.className = 'csound-tooltip-more';
-          more.textContent = `... and ${reference.parameters.length - 5} more`;
-          paramsList.appendChild(more);
-        }
-
         dom.appendChild(paramsList);
       }
 
@@ -126,114 +127,126 @@ export const csoundTooltip = hoverTooltip((view, pos) => {
 
 export const csoundTooltipTheme = EditorView.theme({
   '.cm-tooltip.cm-tooltip-hover': {
-    backgroundColor: 'rgba(0, 0, 0, 0.95)',
+    backgroundColor: 'var(--tooltip-bg)',
     backdropFilter: 'blur(8px)',
-    color: '#ffffff',
-    fontSize: '12px',
-    fontFamily: 'monospace',
+    color: 'var(--color-text-primary)',
+    fontSize: 'var(--font-sm)',
+    fontFamily: 'var(--font-mono)',
     padding: '0',
     maxWidth: '500px',
-    border: '1px solid #3a3a3a',
+    maxHeight: '400px',
+    overflowY: 'auto',
+    border: '1px solid var(--tooltip-border)',
+    borderRadius: 'var(--radius-md)',
+    boxShadow: 'var(--shadow-lg)',
     zIndex: '100'
   },
 
   '.csound-tooltip': {
-    padding: '10px 12px'
+    padding: 'var(--space-md) var(--space-lg)'
   },
 
   '.csound-tooltip-header': {
     display: 'flex',
     alignItems: 'center',
-    gap: '8px',
-    marginBottom: '6px',
-    paddingBottom: '6px',
-    borderBottom: '1px solid #3a3a3a'
+    gap: 'var(--space-sm)',
+    marginBottom: 'var(--space-sm)',
+    paddingBottom: 'var(--space-sm)',
+    borderBottom: '1px solid var(--color-border-subtle)'
   },
 
   '.csound-tooltip-title': {
     fontWeight: '600',
-    color: '#646cff',
-    fontSize: '14px'
+    color: 'var(--color-accent-primary)',
+    fontSize: 'var(--font-md)'
   },
 
   '.csound-tooltip-type': {
-    fontSize: '10px',
-    color: '#9ca3af',
-    backgroundColor: 'rgba(255, 255, 255, 0.1)',
-    padding: '2px 6px',
-    textTransform: 'uppercase'
+    fontSize: 'var(--font-xs)',
+    color: 'var(--color-text-tertiary)',
+    backgroundColor: 'transparent',
+    padding: '0',
+    textTransform: 'lowercase'
   },
 
   '.csound-tooltip-description': {
-    color: '#e5e7eb',
-    lineHeight: '1.5',
-    marginBottom: '8px'
+    color: 'var(--color-text-secondary)',
+    lineHeight: 'var(--leading-relaxed)',
+    marginBottom: 'var(--space-md)',
+    fontSize: 'var(--font-sm)'
   },
 
   '.csound-tooltip-syntax-label': {
-    fontSize: '10px',
-    color: '#9ca3af',
-    marginTop: '8px',
-    marginBottom: '4px',
-    textTransform: 'uppercase',
+    fontSize: 'var(--font-xs)',
+    color: 'var(--color-text-tertiary)',
+    marginTop: 'var(--space-md)',
+    marginBottom: 'var(--space-xs)',
+    textTransform: 'lowercase',
     fontWeight: '500'
   },
 
   '.csound-tooltip-syntax': {
-    backgroundColor: 'rgba(0, 0, 0, 0.4)',
-    color: '#fbbf24',
-    padding: '6px 8px',
-    fontSize: '11px',
-    fontFamily: 'monospace',
-    margin: '0 0 8px 0',
+    backgroundColor: 'var(--code-bg)',
+    color: 'var(--code-text)',
+    padding: 'var(--space-sm) 0 var(--space-sm) var(--space-sm)',
+    fontSize: 'var(--font-sm)',
+    fontFamily: 'var(--font-mono)',
+    margin: '0 0 var(--space-md) 0',
     whiteSpace: 'pre-wrap',
-    lineHeight: '1.4',
-    border: '1px solid #2a2a2a'
+    lineHeight: 'var(--leading-normal)',
+    border: 'none',
+    borderLeft: '2px solid var(--code-border)'
   },
 
   '.csound-tooltip-rates': {
-    fontSize: '11px',
-    color: '#60a5fa',
-    marginBottom: '8px'
+    fontSize: 'var(--font-sm)',
+    color: 'var(--color-info)',
+    marginBottom: 'var(--space-md)'
   },
 
   '.csound-tooltip-params-label': {
-    fontSize: '10px',
-    color: '#9ca3af',
-    marginTop: '8px',
-    marginBottom: '4px',
-    textTransform: 'uppercase',
+    fontSize: 'var(--font-xs)',
+    color: 'var(--color-text-tertiary)',
+    marginTop: 'var(--space-md)',
+    marginBottom: 'var(--space-sm)',
+    textTransform: 'lowercase',
     fontWeight: '500'
   },
 
   '.csound-tooltip-params': {
     display: 'flex',
     flexDirection: 'column',
-    gap: '4px'
+    gap: 'var(--space-md)'
   },
 
   '.csound-tooltip-param': {
     display: 'flex',
-    gap: '6px',
-    fontSize: '11px',
-    lineHeight: '1.4'
+    flexDirection: 'column',
+    gap: 'var(--space-xs)',
+    fontSize: 'var(--font-sm)',
+    lineHeight: 'var(--leading-normal)'
+  },
+
+  '.csound-tooltip-param-header': {
+    display: 'flex',
+    alignItems: 'center',
+    gap: 'var(--space-sm)'
   },
 
   '.csound-tooltip-param-name': {
-    color: '#10b981',
+    color: 'var(--color-text-primary)',
     fontWeight: '500',
-    minWidth: '60px'
+    fontSize: 'var(--font-sm)'
+  },
+
+  '.csound-tooltip-param-type': {
+    color: 'var(--color-text-tertiary)',
+    fontSize: 'var(--font-xs)'
   },
 
   '.csound-tooltip-param-desc': {
-    color: '#d1d5db',
-    flex: '1'
-  },
-
-  '.csound-tooltip-more': {
-    fontSize: '10px',
-    color: '#9ca3af',
-    fontStyle: 'italic',
-    marginTop: '4px'
+    color: 'var(--color-text-secondary)',
+    fontSize: 'var(--font-sm)',
+    lineHeight: 'var(--leading-normal)'
   }
 });
diff --git a/src/lib/editor/codemirror-theme.ts b/src/lib/editor/codemirror-theme.ts
new file mode 100644
index 0000000..60e73d3
--- /dev/null
+++ b/src/lib/editor/codemirror-theme.ts
@@ -0,0 +1,105 @@
+import { EditorView } from '@codemirror/view';
+import type { Extension } from '@codemirror/state';
+import { HighlightStyle, syntaxHighlighting } from '@codemirror/language';
+import { tags as t } from '@lezer/highlight';
+
+function getCSSVariable(name: string): string {
+  if (typeof window === 'undefined') return '';
+  return getComputedStyle(document.documentElement).getPropertyValue(name).trim();
+}
+
+export function createCodeMirrorTheme(): Extension {
+  const editorTheme = EditorView.theme({
+    '&': {
+      backgroundColor: getCSSVariable('--color-bg-base'),
+      color: getCSSVariable('--color-text-primary'),
+    },
+    '.cm-content': {
+      caretColor: getCSSVariable('--color-accent-primary'),
+    },
+    '.cm-cursor, .cm-dropCursor': {
+      borderLeftColor: getCSSVariable('--color-accent-primary'),
+    },
+    '&.cm-focused > .cm-scroller > .cm-selectionLayer .cm-selectionBackground, .cm-selectionBackground, .cm-content ::selection': {
+      backgroundColor: getCSSVariable('--color-selected-overlay'),
+    },
+    '.cm-panels': {
+      backgroundColor: getCSSVariable('--color-surface-1'),
+      color: getCSSVariable('--color-text-primary'),
+    },
+    '.cm-panels.cm-panels-top': {
+      borderBottom: `1px solid ${getCSSVariable('--color-border-default')}`,
+    },
+    '.cm-panels.cm-panels-bottom': {
+      borderTop: `1px solid ${getCSSVariable('--color-border-default')}`,
+    },
+    '.cm-searchMatch': {
+      backgroundColor: getCSSVariable('--color-warning'),
+      outline: `1px solid ${getCSSVariable('--color-border-accent')}`,
+    },
+    '.cm-searchMatch.cm-searchMatch-selected': {
+      backgroundColor: getCSSVariable('--color-accent-primary-subtle'),
+    },
+    '.cm-activeLine': {
+      backgroundColor: getCSSVariable('--color-hover-overlay'),
+    },
+    '.cm-selectionMatch': {
+      backgroundColor: getCSSVariable('--color-selected-overlay'),
+    },
+    '&.cm-focused .cm-matchingBracket, &.cm-focused .cm-nonmatchingBracket': {
+      backgroundColor: getCSSVariable('--color-active-overlay'),
+    },
+    '.cm-gutters': {
+      backgroundColor: getCSSVariable('--color-surface-1'),
+      color: getCSSVariable('--color-text-tertiary'),
+      border: 'none',
+      borderRight: `1px solid ${getCSSVariable('--color-border-subtle')}`,
+    },
+    '.cm-activeLineGutter': {
+      backgroundColor: getCSSVariable('--color-hover-overlay'),
+      color: getCSSVariable('--color-text-secondary'),
+    },
+    '.cm-foldPlaceholder': {
+      backgroundColor: getCSSVariable('--color-surface-2'),
+      border: `1px solid ${getCSSVariable('--color-border-default')}`,
+      color: getCSSVariable('--color-text-secondary'),
+    },
+    '.cm-tooltip': {
+      border: `1px solid ${getCSSVariable('--color-border-default')}`,
+      backgroundColor: getCSSVariable('--color-tooltip-bg'),
+    },
+    '.cm-tooltip .cm-tooltip-arrow:before': {
+      borderTopColor: getCSSVariable('--color-border-default'),
+    },
+    '.cm-tooltip .cm-tooltip-arrow:after': {
+      borderTopColor: getCSSVariable('--color-tooltip-bg'),
+    },
+    '.cm-tooltip-autocomplete': {
+      '& > ul > li[aria-selected]': {
+        backgroundColor: getCSSVariable('--color-selected-overlay'),
+        color: getCSSVariable('--color-text-primary'),
+      },
+    },
+  }, { dark: getCSSVariable('--color-bg-base').startsWith('#1') || getCSSVariable('--color-bg-base').startsWith('#2') });
+
+  const highlightStyle = HighlightStyle.define([
+    { tag: t.keyword, color: getCSSVariable('--color-accent-primary') },
+    { tag: [t.name, t.deleted, t.character, t.propertyName, t.macroName], color: getCSSVariable('--color-text-primary') },
+    { tag: [t.function(t.variableName), t.labelName], color: getCSSVariable('--color-info') },
+    { tag: [t.color, t.constant(t.name), t.standard(t.name)], color: getCSSVariable('--color-warning') },
+    { tag: [t.definition(t.name), t.separator], color: getCSSVariable('--color-text-primary') },
+    { tag: [t.typeName, t.className, t.number, t.changed, t.annotation, t.modifier, t.self, t.namespace], color: getCSSVariable('--color-warning') },
+    { tag: [t.operator, t.operatorKeyword, t.url, t.escape, t.regexp, t.link, t.special(t.string)], color: getCSSVariable('--color-accent-primary-hover') },
+    { tag: [t.meta, t.comment], color: getCSSVariable('--color-text-tertiary'), fontStyle: 'italic' },
+    { tag: t.strong, fontWeight: 'bold' },
+    { tag: t.emphasis, fontStyle: 'italic' },
+    { tag: t.strikethrough, textDecoration: 'line-through' },
+    { tag: t.link, color: getCSSVariable('--color-info'), textDecoration: 'underline' },
+    { tag: t.heading, fontWeight: 'bold', color: getCSSVariable('--color-accent-primary') },
+    { tag: [t.atom, t.bool, t.special(t.variableName)], color: getCSSVariable('--color-warning') },
+    { tag: [t.processingInstruction, t.string, t.inserted], color: getCSSVariable('--color-success') },
+    { tag: t.invalid, color: getCSSVariable('--color-error') },
+  ]);
+
+  return [editorTheme, syntaxHighlighting(highlightStyle)];
+}
diff --git a/src/lib/stores/editorSettings.ts b/src/lib/stores/editorSettings.ts
index f11a6d3..4114f7c 100644
--- a/src/lib/stores/editorSettings.ts
+++ b/src/lib/stores/editorSettings.ts
@@ -2,6 +2,8 @@ import { writable } from 'svelte/store';
 
 const STORAGE_KEY = 'editorSettings';
 
+export type Theme = 'dark' | 'light';
+
 export interface EditorSettings {
   fontSize: number;
   fontFamily: string;
@@ -9,6 +11,8 @@ export interface EditorSettings {
   enableLineWrapping: boolean;
   tabSize: number;
   vimMode: boolean;
+  enableHoverTooltips: boolean;
+  theme: Theme;
 }
 
 const defaultSettings: EditorSettings = {
@@ -17,7 +21,9 @@ const defaultSettings: EditorSettings = {
   showLineNumbers: true,
   enableLineWrapping: false,
   tabSize: 2,
-  vimMode: false
+  vimMode: false,
+  enableHoverTooltips: true,
+  theme: 'dark'
 };
 
 export interface EditorSettingsStore {
diff --git a/src/lib/stores/uiState.svelte.ts b/src/lib/stores/uiState.svelte.ts
index 533ee99..4cbe04a 100644
--- a/src/lib/stores/uiState.svelte.ts
+++ b/src/lib/stores/uiState.svelte.ts
@@ -30,10 +30,18 @@ export class UIState {
     this.scopePopupVisible = true;
   }
 
+  toggleScope() {
+    this.scopePopupVisible = !this.scopePopupVisible;
+  }
+
   openSpectrogram() {
     this.spectrogramPopupVisible = true;
   }
 
+  toggleSpectrogram() {
+    this.spectrogramPopupVisible = !this.spectrogramPopupVisible;
+  }
+
   showShare(url: string) {
     this.shareUrl = url;
     this.sharePopupVisible = true;
diff --git a/src/main.ts b/src/main.ts
index 664a057..4714619 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1,7 +1,22 @@
 import { mount } from 'svelte'
+import './theme.css'
 import './app.css'
 import App from './App.svelte'
 
+// Apply saved theme before mounting app
+const STORAGE_KEY = 'editorSettings';
+const stored = localStorage.getItem(STORAGE_KEY);
+if (stored) {
+  try {
+    const settings = JSON.parse(stored);
+    if (settings.theme) {
+      document.documentElement.dataset.theme = settings.theme;
+    }
+  } catch (e) {
+    console.error('Failed to parse editor settings:', e);
+  }
+}
+
 const app = mount(App, {
   target: document.getElementById('app')!,
 })
diff --git a/src/theme.css b/src/theme.css
new file mode 100644
index 0000000..369a708
--- /dev/null
+++ b/src/theme.css
@@ -0,0 +1,169 @@
+/* Theme System */
+
+/* Dark Theme - Default */
+:root,
+[data-theme="dark"] {
+  /* Base Colors */
+  --color-bg-base: #1a1a1a;
+  --color-bg-elevated: #242424;
+  --color-bg-overlay: #2a2a2a;
+  --color-bg-input: #1e1e1e;
+
+  /* Surface Colors */
+  --color-surface-0: #1a1a1a;
+  --color-surface-1: #202020;
+  --color-surface-2: #252525;
+  --color-surface-3: #2a2a2a;
+
+  /* Text Colors */
+  --color-text-primary: rgba(255, 255, 255, 0.87);
+  --color-text-secondary: rgba(255, 255, 255, 0.6);
+  --color-text-tertiary: rgba(255, 255, 255, 0.4);
+  --color-text-disabled: rgba(255, 255, 255, 0.25);
+
+  /* Accent Colors */
+  --color-accent-primary: #646cff;
+  --color-accent-primary-hover: #818cf8;
+  --color-accent-primary-active: #535bf2;
+  --color-accent-primary-subtle: rgba(100, 108, 255, 0.1);
+
+  /* Semantic Colors */
+  --color-success: #10b981;
+  --color-warning: #fbbf24;
+  --color-error: #ef4444;
+  --color-info: #60a5fa;
+
+  /* Border Colors */
+  --color-border-subtle: rgba(255, 255, 255, 0.06);
+  --color-border-default: rgba(255, 255, 255, 0.1);
+  --color-border-strong: rgba(255, 255, 255, 0.2);
+  --color-border-accent: var(--color-accent-primary);
+
+  /* Interactive States */
+  --color-hover-overlay: rgba(255, 255, 255, 0.05);
+  --color-active-overlay: rgba(255, 255, 255, 0.08);
+  --color-selected-overlay: rgba(100, 108, 255, 0.15);
+
+  /* Shadows */
+  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.2);
+  --shadow-md: 0 2px 4px rgba(0, 0, 0, 0.3);
+  --shadow-lg: 0 4px 12px rgba(0, 0, 0, 0.4);
+
+  /* Component Specific */
+  --accordion-header-bg: transparent;
+  --accordion-header-hover: var(--color-hover-overlay);
+  --accordion-border: var(--color-border-subtle);
+
+  --input-bg: var(--color-bg-input);
+  --input-border: var(--color-border-default);
+  --input-border-focus: var(--color-accent-primary);
+
+  --tooltip-bg: rgba(32, 32, 32, 0.98);
+  --tooltip-border: var(--color-border-default);
+
+  --code-bg: transparent;
+  --code-border: var(--color-border-subtle);
+  --code-text: var(--color-text-secondary);
+}
+
+/* Light Theme */
+[data-theme="light"] {
+  /* Base Colors */
+  --color-bg-base: #fafafa;
+  --color-bg-elevated: #ffffff;
+  --color-bg-overlay: #f5f5f5;
+  --color-bg-input: #ffffff;
+
+  /* Surface Colors */
+  --color-surface-0: #fafafa;
+  --color-surface-1: #ffffff;
+  --color-surface-2: #f5f5f5;
+  --color-surface-3: #eeeeee;
+
+  /* Text Colors */
+  --color-text-primary: rgba(0, 0, 0, 0.87);
+  --color-text-secondary: rgba(0, 0, 0, 0.6);
+  --color-text-tertiary: rgba(0, 0, 0, 0.4);
+  --color-text-disabled: rgba(0, 0, 0, 0.25);
+
+  /* Accent Colors */
+  --color-accent-primary: #5865f2;
+  --color-accent-primary-hover: #4752c4;
+  --color-accent-primary-active: #3c45a5;
+  --color-accent-primary-subtle: rgba(88, 101, 242, 0.1);
+
+  /* Semantic Colors */
+  --color-success: #059669;
+  --color-warning: #d97706;
+  --color-error: #dc2626;
+  --color-info: #2563eb;
+
+  /* Border Colors */
+  --color-border-subtle: rgba(0, 0, 0, 0.08);
+  --color-border-default: rgba(0, 0, 0, 0.12);
+  --color-border-strong: rgba(0, 0, 0, 0.24);
+  --color-border-accent: var(--color-accent-primary);
+
+  /* Interactive States */
+  --color-hover-overlay: rgba(0, 0, 0, 0.04);
+  --color-active-overlay: rgba(0, 0, 0, 0.08);
+  --color-selected-overlay: rgba(88, 101, 242, 0.12);
+
+  /* Shadows */
+  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.08);
+  --shadow-md: 0 2px 4px rgba(0, 0, 0, 0.12);
+  --shadow-lg: 0 4px 12px rgba(0, 0, 0, 0.15);
+
+  /* Component Specific */
+  --accordion-header-bg: transparent;
+  --accordion-header-hover: var(--color-hover-overlay);
+  --accordion-border: var(--color-border-subtle);
+
+  --input-bg: var(--color-bg-input);
+  --input-border: var(--color-border-default);
+  --input-border-focus: var(--color-accent-primary);
+
+  --tooltip-bg: rgba(255, 255, 255, 0.98);
+  --tooltip-border: var(--color-border-default);
+
+  --code-bg: transparent;
+  --code-border: var(--color-border-subtle);
+  --code-text: var(--color-text-secondary);
+}
+
+/* Shared Variables */
+:root {
+  /* Spacing Scale */
+  --space-xs: 0.25rem;
+  --space-sm: 0.5rem;
+  --space-md: 0.75rem;
+  --space-lg: 1rem;
+  --space-xl: 1.5rem;
+  --space-2xl: 2rem;
+
+  /* Border Radius */
+  --radius-sm: 2px;
+  --radius-md: 4px;
+  --radius-lg: 6px;
+
+  /* Font Sizes */
+  --font-xs: 0.6875rem;
+  --font-sm: 0.75rem;
+  --font-md: 0.8125rem;
+  --font-base: 0.875rem;
+  --font-lg: 1rem;
+
+  /* Font Families */
+  --font-mono: 'Courier New', Monaco, Consolas, monospace;
+  --font-sans: system-ui, -apple-system, sans-serif;
+
+  /* Line Heights */
+  --leading-tight: 1.4;
+  --leading-normal: 1.5;
+  --leading-relaxed: 1.6;
+
+  /* Transitions */
+  --transition-fast: 100ms ease;
+  --transition-base: 200ms ease;
+  --transition-slow: 300ms ease;
+}