a mixin for styling html placeholders

placeholder-mixin.less

// placeholder styles
.placeholder(@color:inherit, @background: inherit) {
  ::-webkit-input-placeholder {
    color: @color;
    background: @background;
  }

  :-moz-placeholder { /* Firefox 18- */
    color: @color;
    background: @background;
  }

  ::-moz-placeholder {  /* Firefox 19+ */
    color: @color;
    background: @background;
  }

  :-ms-input-placeholder {  
    color: @color;
    background: @background;
  }
}