@mixin keyframes($name) {
  @keyframes #{$name} { @content; }
}

@mixin pulse-keyframes($color) {
  @include keyframes(pulse) {
    0% {
      box-shadow: 0 0 0 0 $color;
    }
    70% {
      box-shadow: 0 0 0 10px $color;
    }
    100% {
      box-shadow: 0 0 0 0 $color;
    }
  }
}