Fix side bar size and add confirm box to removing subscriptions

src/style/main.css

@@ -387,7 +387,7 @@ a {
 }
 
 #sideNav {
-    height: 93vh;
+    height: calc(100vh - 60px);
     width: 250px;
     overflow-y: auto;
     position: fixed;

src/templates/subscriptions.html

@@ -16,5 +16,5 @@
 -->
 <li onclick='goToChannel("{{channelId}}")'>
     <img src='{{channelIcon}}' /> {{channelName}}
-    <i class='fas fa-times' onclick='event.stopPropagation();removeSubscription("{{channelId}}")'></i>
+    <i class='fas fa-times' onclick='event.stopPropagation();confirmFunction("Are you sure you want to remove this channel from your subscriptions?", removeSubscription, "{{channelId}}")'></i>
 </li>