.grayscale {
  /* Firefox 10+, Firefox on Android */
  filter: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg'><filter id='grayscale'><feColorMatrix type='matrix' values='0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0 0 0 1 0'/></filter></svg>#grayscale");

  /* IE 6-9 */
  filter: gray;

  /*
    Chrome 19+,
    Safari 6+,
    Safari 6+ iOS,
    Opera 15+
  */
  -webkit-filter: grayscale(100%);

      -webkit-transition-property: color, text;
    -webkit-transition-duration: 0.3s, 0.3s;
    -webkit-transition-timing-function: linear, ease-in;
    -moz-transition-property: color, text;
    -moz-transition-duration: 0.3s;
    -moz-transition-timing-function: linear, ease-in;
    -o-transition-property: color, text;
    -o-transition-duration: 0.3s;
    -o-transition-timing-function: linear, ease-in;
}