Custom scrollbar only in one div

#boardslist {

  &::-webkit-scrollbar {
   width: 0.5em;
   height: 0.5em;
  }

  &::-webkit-scrollbar-thumb {
   background-color: rgba(255,255,255,.1);
   border-radius: 3px;

   &:hover {
    background: rgba(255,255,255,.2);
   }
  }
}

Check this out http://codepen.io/tholman/pen/tldwm