add/close toggle admin button icon

_index.html

@@ -30,8 +30,8 @@
         <h1 id='itolo'>PingPong '19</h1>
         <!-- <a href='admin.php' class='adminButton'> -->
         <!-- <a href='#' onclick="$('#menu').collapse('toggle')" class='adminButton'> -->
-        <a href='#' onclick="$('#menu').slideToggle()" class='adminButton'>
-            <ion-icon size='large' name='add'></ion-icon>
+        <a href='#' onclick="$('#menu').slideToggle();$('#admin_icon').toggleClass('active')" class='adminButton'>
+            <ion-icon id="admin_icon" size='large' name='add'></ion-icon>
         </a>
     </span>
 

css/main.css

@@ -99,6 +99,15 @@ p.centered {
     transition: all .3s;
     color: #999;
 }
+#admin_icon {
+    transform: none;
+    transition: all .3s .1s;
+    transform-origin: 50% 50%;
+}
+#admin_icon.active {
+    transition: all .3s;
+    transform: rotate(45deg);
+}
 .adminButton:hover, .adminButton:active {
     color: #777;
     background: #ebebeb;