Reconfigure z-index hierarchy: show dropdowns above post composer

less/forum/DiscussionPage.less

@@ -128,7 +128,6 @@
   .DiscussionPage-list {
     .panePinned & {
       left: 0;
-      z-index: @zindex-composer - 1;
       .transition(none);
     }
   }

less/forum/Post.less

@@ -263,7 +263,6 @@
   margin-top: -5px;
   float: right;
   position: relative;
-  z-index: 1;
   .transition(opacity 0.2s);
 
   .EventPost &, .Post--hidden:not(.revealContent) & {
@@ -288,9 +287,6 @@
   .Post:hover &, &.open {
     opacity: 1;
   }
-  &.open {
-    z-index: 2;
-  }
 }
 
 .PostPreview {