gistfile1.sass

@mixin invert($amt: 100%) {
  -o-filter: invert($amt);
  -ms-filter: invert($amt);
  -moz-filter: invert($amt);
  -webkit-filter: invert($amt);
  
  @-moz-document url-prefix() { 
	filter: url("data:image/svg+xml;utf8,<svg xmlns=\'http://www.w3.org/2000/svg\'><filter id=\'invert\'><feColorMatrix in='SourceGraphic' type='matrix' values='-1 0 0 0 1 0 -1 0 0 1 0 0 -1 0 1 0 0 0 1 0'/></filter></svg>#invert");
	background-color: #000;
  }
}