energylink/public/sass/mixins/_buttons.scss

// Button backgrounds
// ------------------
@mixin buttonBackground($startColor, $endColor, $text-color: #fff, $textShadow: 0 -1px 0 rgba(0,0,0,.25)) {
  // gradientBar will set the background to a pleasing blend of these, to support IE<=9
  @include gradientBar($startColor, $endColor, $text-color, $textShadow);

  box-shadow: inset 0 -4px rgba(0,0,0,0.3);

  // in these cases the gradient won't cover the background, so we override
  &:hover, &:focus, &:active, &.active, &.disabled, &[disabled] {
    color: $text-color;
    background-image: none;
    background-color: darken($endColor, 2%);
  }
}