html {

 -ms-filter: grayscale(100%);

 -webkit-filter: grayscale(100%);

 -moz-filter: grayscale(100%);

 -o-filter: grayscale(100%);

 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\'></fecolormatrix></filter></svg>#grayscale");

 filter: gray;

 }