web网站所有元素变灰色

//给html或者*设置下面的颜色即可
          -webkit-filter: grayscale(100%);
          -moz-filter: grayscale(100%);
          -ms-filter: grayscale(100%);
          -o-filter: grayscale(100%);
          filter: grayscale(100%);
          filter: gray;


--------            
//恢复彩色
            -webkit-filter: grayscale(0);
            -moz-filter: grayscale(0);
            -ms-filter: grayscale(0);
            -o-filter: grayscale(0);
            filter: grayscale(0);