div {
        background-color: #666;
        color: #fff;
        h: expression(onmouseover=new Function("this.style.backgroundColor='#ff0'; this.style.color='#000';"),
                       onmouseout=new Function("this.style.backgroundColor='#666'; this.style.color='#fff';"));
    }
    div:hover {
        background-color: #ff0;
        color: #000;
    }

<div>BASIC CSS</div>