<style> 
    html { 
        -webkit-filter: grayscale(100%); 
        -moz-filter: grayscale(100%); 
        -ms-filter: grayscale(100%); 
        -o-filter: grayscale(100%); 
        filter:progid:DXImageTransform.Microsoft.BasicImage(grayscale=1);  
        _filter:none; 
    } 
</style>