(Quick)Fix vertical-center breakpoints for smaller screens (#4773)

* Quickfix: adjust vertical-center class for smaller screens

* Add Margin Bottom to RoomJoin

* Fix padding size

* Fix padding size

* Remove Bottom Margin on RoomJoin

* Add breakpoint to vertical-buffer

app/assets/stylesheets/helpers.scss

@@ -17,6 +17,10 @@
   right: 0;
   margin: auto;
   height: 75%;
+
+  @include media-breakpoint-down(xxl) {
+    height: 85%;
+  }
 }
 
 .no-header-height {
@@ -24,6 +28,10 @@
 
   .vertical-buffer {
     padding-top: 10%;
+
+    @include media-breakpoint-down(xxl) {
+      height: 5%;
+    }
   }
 }
 
@@ -32,6 +40,10 @@
 
   .vertical-buffer {
     padding-top: 5%;
+
+    @include media-breakpoint-down(xxl) {
+      height: 3%;
+    }
   }
 }