dc-sdk/modules/themes/tooltip.scss

.dc-tool-tip {
  position: absolute;
  left: 0;
  top: 0;
  min-width: 100px;
  height: 30px;
  line-height: 30px;
  color: #fff;
  padding: 0 10px;
  background: rgba(0, 0, 0, 0.6);
  border-radius: 4px;
  visibility: hidden;
  pointer-events: none;
  z-index: -1;
  &:before {
    content: '';
    display: block;
    position: absolute;
    pointer-events: none;
    left: -10px;
    top: 5px;
    border-top: 10px solid transparent;
    border-bottom: 10px solid transparent;
    border-right: 10px solid rgba(0, 0, 0, 0.6);
  }
}