@mixin bevel($dark: true,
             $has-bottom: true,
             $bottom-strength: -1px
             ) {
  // Generates the three or one shadows for "rounded materials":
  // One on top, one on bottom and one in the back

  // $dark: use 'false' if using on a bright material
  // $has-bottom: use 'false' if no bottom shadows are needed
  // $bottom-strenght: vary the size of the bottom shadow

  $inset-top-color: rgba(255, 255, 255, .30); //0.16
  $inset-bottom-color: rgba(39, 39, 39, .22); //0.14
  $drop-color:rgba(0, 0, 0, .22); //0.22

  @if not($dark) { // for bright buttons
    $inset-top-color: rgba(255, 255, 255, .8);
    $inset-bottom-color: rgba(39, 39, 39, .10);
    $drop-color: rgba(0, 0, 0, .05);
  }


  @if ($has-bottom) {
    box-shadow: inset 0 1px 0 0 $inset-top-color,
                inset 0 $bottom-strength 0 0 $inset-bottom-color,
                0 1px 3px 0 $drop-color;
  } @else {
    box-shadow: inset 0 1px 0 0 $inset-top-color;
  }
}

@mixin button-bevel() {
  @include bevel();
  text-shadow: 1px 1px 0 $colored-button-text-shadow;

  &.btn-lg {
    @include bevel($bottom-strength: -2px);
  }
}