css使网页变为灰度

html {
   -webkit-filter: grayscale(100%); 
	-moz-filter: grayscale(100%); 
	-ms-filter: grayscale(100%); 
	-o-filter: grayscale(100%); 
	filter:progid:DXImageTransform.Microsoft.BasicImage(grayscale=1); 
	_filter:none; 

}