Fix sidebar collapse button

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/assets/stylesheets/generic/sidebar.scss

@@ -125,7 +125,7 @@
 
     .collapse-nav a {
       left: 0px;
-      padding: 7px 23px 3px 22px;
+      width: 52px;
     }
   }
 }
@@ -137,9 +137,9 @@
   font-size: 13px;
   background: transparent;
   width: 32px;
-  height: 32px;
+  height: 28px;
   text-align: center;
-  line-height: 32px;
+  line-height: 28px;
 }
 
 .collapse-nav a:hover {