<img src="http://www.baidu.com/img/420b_ead78e6081de7939cdf8eff9e608617f.gif" width="270" height="129"><style>html {filter:progid:DXImageTransform.Microsoft.BasicImage(grayscale=1);-webkit-filter: grayscale(100%);}</style>怎样把网站变为灰色的代码