message: make tooltip text color brighter
diff: border-radius: 10px;
  padding: 10px 20px 10px 12px;
  z-index: 2;
  - color: @nav-half-muted-color;
  + color: #DBDFEC;
  line-height: 1;
  opacity: 0;
  transition: opacity 200ms ease-in-out;
  