remove I'm done button when clicked

public/index.html

@@ -16,7 +16,7 @@
                 <dt class="list-group-item">Current Prompt</dt>
                 <dd class="list-group-item"></dd>
             </dl>
-            <button class="btn btn-lg btn-block btn-primary mt-5" disabled>I'm Done</button>
+            <button class="btn btn-lg btn-block btn-primary mt-5 invisible">I'm Done</button>
         </main>
         <script src="/socket.io/socket.io.js"></script>
         <script src="/js/index.js" charset="utf-8"></script>

public/js/index.js

@@ -13,6 +13,7 @@ socket.on('prompt sent', function (prompt) {
     if(prompt !== document.querySelector('dd').innerHTML){
         if(prompt !== "Nothing Yet"){
             button.removeAttribute("disabled");
+            button.classList.remove("invisible");
         }
         document.querySelector('dd').innerHTML = prompt;
     }
@@ -26,6 +27,7 @@ socket.on('disconnect students', function (prompt) {
 
 button.addEventListener('click', (event)=>{
     button.setAttribute("disabled",true);
+    button.classList.add("invisible");
     socket.emit('prompt completed', username);
 });