CSS cleanup and refactoring

app/assets/stylesheets/framework/sidebar.scss

@@ -82,15 +82,13 @@
   }
 }
 
-@mixin sidebar-container {
-  width: calc(100% + 100px);
-}
-
 .right-sidebar {
   border-left: 1px solid $border-color;
 
-  .sidebar-container {
-    @include sidebar-container;
+  .sidebar-container,
+  .issuable-sidebar {
+    // Add 100px so that potentially visible vertical scroll bar is hidden
+    width: calc(100% + 100px);
   }
 }
 
@@ -137,7 +135,6 @@
 
   .issuable-sidebar {
     padding: 0 3px;
-    width: calc(100% + 35px);
   }
 }
 

app/assets/stylesheets/pages/issuable.scss

@@ -309,7 +309,6 @@
   }
 
   .issuable-sidebar {
-    @include sidebar-container;
     height: 100%;
     overflow-y: scroll;
     overflow-x: hidden;