Update index.html

Author: gaimerI

index.html

@@ -116,6 +116,7 @@
         <main>
             <textarea id="input" wrap="off" spellcheck="false" autocapitalize="off" autocomplete="off" autocorrect="off" rows="15"></textarea>
             <div id="preview" class="line-numbers linkable-line-numbers"></div>
+            <div class="threedee"></div>
         </main>
 
         <div id="error-output"></div>