Fix CSS for code highlighting

app/assets/stylesheets/gitlab_bootstrap/files.scss

@@ -95,8 +95,8 @@
         pre {
           padding:0;
           margin:0;
-          background:none;
           border:none;
+          border-radius: 0;
         }
       }
     }
@@ -142,8 +142,8 @@
         table-layout: fixed;
 
         pre {
-          background: none;
           border: none;
+          border-radius: 0;
           font-family: 'Menlo', 'Liberation Mono', 'Consolas', 'Courier New', 'andale mono','lucida console',monospace;
           font-size: 12px !important;
           line-height: 16px !important;

app/assets/stylesheets/highlight/dark.scss

-.black .lines .highlight {
-  background: #333;
-  pre { color: #eee; }
+.black .highlight {
+  pre {
+    background-color: #333;
+    color: #eee;
+  }
 
   .hll { display: block; background-color: darken($hover, 65%) }
   .c { color: #888888; font-style: italic } /* Comment */

app/assets/stylesheets/highlight/white.scss

-.white .lines .highlight {
-  background: white;
-  pre { color: #333; }
+.white .highlight {
+  pre {
+    background-color: #fff;
+    color: #333;
+  }
 
   .hll { display: block; background-color: $hover }
   .c { color: #888888; font-style: italic } /* Comment */