fix that powered by category was not opened

css/stylesheet.css

@@ -45,7 +45,7 @@ button {
 }
 
 button:hover {
-    background: rgba(0, 0, 0, .15);
+    background: rgba(0, 0, 0, .15) !important;
 }
 
 button.active {

index.html

@@ -40,7 +40,8 @@
         <a href="https://github.com/parkjs814/AlgorithmVisualizer/wiki">
             <button><i class="fa fa-book"></i> Documentation</button>
         </a>
-        <button class="category"><i class="fa fa-github"></i> Powered by ...</button>
+        <button class="category" id="powered-by"><i class="fa fa-github"></i> Powered by ...</button>
+        <div id="powered-by-list">
             <a href="https://github.com/jquery/jquery">
                 <button class="indent">jquery/jquery</button>
             </a>
@@ -56,7 +57,7 @@
             <a href="https://github.com/simonwhitaker/github-fork-ribbon-css">
                 <button class="indent">simonwhitaker/github-fork-ribbon-css</button>
             </a>
-
+        </div>
     </div>
     <a class="github-fork-ribbon left-bottom" href="http://github.com/parkjs814/AlgorithmVisualizer"
        title="Fork me on GitHub">Fork me on GitHub</a>

js/script.js

@@ -178,6 +178,9 @@ $.getJSON('./algorithm/category.json', function (data) {
         })(category);
     }
 });
+$('#powered-by').click(function () {
+    $('#powered-by-list button').toggleClass('collapse');
+});
 
 var sidemenu_percent;
 $('#navigation').click(function () {