@mixin animation($rule) {
  -webkit-animation: $rule;
  -moz-animation: $rule;
  -o-animation: $rule;
  animation: $rule;
}

@mixin keyframes( $animation-name) {
  @-webkit-keyframes #{$animation-name} {
    @content;
  }
  @-moz-keyframes #{$animation-name} {
    @content;
  }
  @-o-keyframes #{$animation-name} {
    @content;
  }
  @keyframes #{$animation-name} {
    @content;
  }
}