Css editor snippet

gistfile1.js

javascript:document.body.appendChild(
    (function(s){
        s.setAttribute('contenteditable','');
        s.setAttribute('style','display:block; border:1px solid black; width:90%; height:300px; position:fixed; bottom:50px; left:5%; z-index:65536;');
        s.setAttribute('onkeydown','event.stopPropagation()');
        s.setAttribute('onkeypress','event.stopPropagation()');
        s.setAttribute('onkeyup','event.stopPropagation()');
        return s;
    })(document.createElement('style'))
);