$tooltip-color: transparentize($dark-gray, 0.1);
$tooltip-placement: top; // "top" or "bottom"

@mixin tooltip($position) {
  position: relative;
  $opposite-position: bottom;

  @if ($position == top) {
    $opposite-position: bottom;
  }

  @else if ($position == bottom) {
    $opposite-position: top;
  }

  &:hover {
    .tooltip {
      opacity: 1;
      visibility: visible;
    }
  }

  .tooltip {
    background-color: $tooltip-color;
    box-sizing: border-box;
    color: white;
    font-weight: normal;
    opacity: 0;
    padding: 0.5em 1em;
    border-radius: $base-border-radius;
    position: absolute;
    text-align: center;
    text-overflow: ellipsis;
    text-shadow: 0 1px 0 darken(rgb(80,80,80), 4%);
    text-transform: none;
    transition: all 0.15s linear;
    white-space: nowrap;
    visibility: hidden;
    width: 200px;
    z-index: 10;
    #{$position}: -50px;
    left: 50%;
    margin-left: -(200px/2);

    &:before,
    &:after {
      display: block;
      pointer-events: none;
      position: absolute;
      width: 0;
      height: 0;
      content: '';
      border: 8px solid transparent;
    }

    &:before {
      top: auto;
      bottom: -18px;
      left: auto;
      right: auto;
      left: 50%;
      margin-left: -(8px + 1);
    }

    &:after {
      border-#{$position}-color: $tooltip-color;
      $position: auto;
      #{$opposite-position}: -16px;
      left: auto;
      right: auto;
      left: 50%;
      margin-left: -8px;
    }
  }
}

a.tooltip-item {
  @include button(simple, lighten($light-gray, 10));
  @include tooltip($tooltip-placement);
  font-size: $base-font-size;
}