ui element for theme switching

index.html

@@ -300,6 +300,12 @@
                     <option value="Steps Mono Thin">Steps Mono Thin</option>
                   </select>
               </div>
+              <div class="gray-200 rounded-lg ml-0 lg:w-1/3 w-full pt-2 pb-1 mb-2">
+                <label for="theme" class="block ml-5 mb-2 font-medium sd:text-sm">Theme:</label>
+                  <select id="theme-selector" class="gray-50 ml-4 border border-gray-300 mb-2
+                  text-gray-900 text-sm rounded-lg  focus:border-blue-500 block  p-2.5 gray-700 border-gray-600 placeholder-gray-400 ">
+                  </select>
+              </div>
               <!-- Editor mode selection -->
             <div class="gray-200 rounded-lg lg:ml-4 lg:w-1/3 w-full pt-2 pb-1 mb-2">
               <p class="font-bold lg:text-xl text-sm ml-4 pb-4 underline underline-offset-4">Editor options</p>