placeholderにスタイルを当てるSCSS Mixin

@mixin placeholder-style {
  &::-webkit-input-placeholder {
    @content;
  }

  // Firefox 4 to 18
  &:-moz-placeholder {
    opacity:  1;
    @content;
  }

  // Firefox 19+
  &::-moz-placeholder {
    opacity:  1;
    @content;
  }

  // IE 10+
  &:-ms-input-placeholder {
    @content;
  }
}

Example

.text-input {
  @include placeholder-style {
    color: $color;
  };
}