css: Show 'x' button hover styling when hovered over 'x'.

When input pills are hovered, the 'x' button is highlighted.
This commit ensures that 'x' button is highlighted only if the
'x' button is hovered, not anywhere else on the pill.

Author: ecxtacy <dc.dhruvchouhan@gmail.com>.

web/styles/input_pill.css

@@ -62,7 +62,7 @@
             margin-right: 3px;
         }
 
-        &:hover .exit {
+        .exit:hover {
             opacity: 1;
         }
     }