<style>
    html{
        filter: grayscale(100%); -webkit-filter: grayscale(100%);
        -moz-filter: grayscale(100%); -ms-filter: grayscale(100%);
        -o-filter: grayscale(100%); filter: url("data:image/svg+xml;utf8,#grayscale");
        filter:progid:DXImageTransform.Microsoft.BasicImage(grayscale=1);
        -webkit-filter: grayscale(1);
    }
</style>

特殊日期网站变灰