OnMouseOver Background Menggunakan Javascript

<div id="mydiv" style="width:200px;background:white" onmouseover="this.style.background='gray';" onmouseout="this.style.background='white';">
    Jack and Jill went up the hill
    To fetch a pail of water.
    Jack fell down and broke his crown,
    And Jill came tumbling after.
    </div>