Triangle with shadow

trianglw_shadow.scss

.tooltip {
  background-color: #fff;

  &:after {
    bottom: -9px;
    border: 8px solid;
    border-color: transparent transparent #fff #fff;
    box-shadow: -3px 3px 3px 0 #aaa;
    content: "";
    height: 0;
    left: 50%;
    position: absolute;
    transform-origin: 0 0;
    transform: rotate(-45deg) translateX(-50%);
    width: 0;
  }
}