CSS：各大网站实现灰度的方法

[smileyby]

-webkit-filter: grayscale(100%);
-moz-filter: grayscale(100%);
-ms-filter: grayscale(100%);
-o-filter: grayscale(100%);
filter: grayscale(100%);
filter: gray;
filter: url(data:image/svg+xml;utf8,#grayscale); /* 腾讯 /
filter: progid:DXImageTransform.Microsoft.BasicImage(grayscale=1); / 抖音、淘宝、京东、美团、网易、去哪儿、滴滴 */