Darken text on light gray bgs

`#666` meets AA while the updated `#767676` doesn't against `#eee`

Author: mdo

scss/_counter.scss

@@ -4,7 +4,7 @@
   font-size: 11px;
   font-weight: bold;
   line-height: 1;
-  color: $brand-gray;
+  color: #666;
   background-color: #eee;
   border-radius: 20px;
 }