@keyframes tooltipBackgroundShow {
  0% {
    transform: scale(0.2);
    opacity: 0.25;
  }
  50% {
    opacity: 1;
  }
  100% {
    transform: scale(1.0);
    opacity: 1;
  }
}
@keyframes tooltipBackgroundHide {
  0% { opacity: 1; }
  100% { opacity: 0; }
}

md-tooltip {
  position: absolute;
  font-size: 14px;
  z-index: $z-index-tooltip;
  overflow: hidden;
  pointer-events: none;
  border-radius: 4px;

  &[md-direction="bottom"] {
    transform: translate3d(0, -30%, 0);
    margin-top: 8px;
  }
  &[md-direction="top"] {
    transform: translate3d(0, 30%, 0);
    margin-bottom: 8px;
  }

  .md-background {
    position: absolute;
    left: 50%;
    width: 256px;
    height: 256px;
    margin-left: -128px;
    margin-top: -128px;
    border-radius: 256px;

    opacity: 0.25;
    transform: scale(0.2);
  }

  .md-content {
    max-width: 240px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;

    padding: 8px;
    background: transparent;
    opacity: 0.3;
    transition: inherit;
  }

  &.md-hide {
    transition: $swift-ease-in;
  }

  &.md-show {
    transition: $swift-ease-out;
    pointer-events: auto;
    transform: translate3d(0,0,0);

    .md-background {
      transform: scale(1.0);
      opacity: 1.0;
      animation: tooltipBackgroundShow linear;
    }
    .md-content {
      opacity: 0.99;
    }
  }
  &.md-hide .md-background {
    transform: scale(1.0);
    opacity: 0;
    animation: tooltipBackgroundHide 0.2s linear;
  }

  /**
   * Depending on the tooltip's size as a multiple of 32 (set by JS),
   * change the background's animation duration.
   * The larger the tooltip, the less time the background should take to ripple outwards.
   */
  @for $i from 1 through 8 {
    &[width-32="#{$i}"].md-show .md-background {
      $duration: 1000 - $i * 100;
      animation-duration: #{$duration}ms;
    }
  }
}