<style>
         html{
            filter: grayscale(100%);
            -webkit-filter: grayscale(100%);
            -moz-filter: grayscale(100%);
            -ms-filter: grayscale(100%);
            -o-filter: grayscale(100%);
            filter:progid:DXImageTransform.Microsoft.BasicImage(grayscale=1);
        }
        
</style>