Highlight comment bar for comments considered mentions (#3938)

webapp/utils/utils.jsx

@@ -663,9 +663,7 @@ export function applyTheme(theme) {
 
     if (theme.mentionHighlightBg) {
         changeCss('.app__body .mention--highlight, .app__body .search-highlight', 'background:' + theme.mentionHighlightBg, 1);
-    }
-
-    if (theme.mentionHighlightBg) {
+        changeCss('.mention-comment', 'border-color:' + theme.mentionHighlightBg + ' !important', 1);
         changeCss('.app__body .post.post--highlight', 'background:' + changeOpacity(theme.mentionHighlightBg, 0.5), 1);
     }
 
@@ -1375,4 +1373,4 @@ export function handleFormattedTextClick(e) {
             browserHistory.push(linkAttribute.value);
         }
     }
-}
+}