div background color, to change onhover

I'm trying to make a div's background color change on mouse over.

the div {background:white;}
the div a:hover{background:grey; width:100%;
display:block; text-decoration:none;}

only the link inside the div gets the background color.

what could I do to make the whole div get that background color?

thank you

EDIT :
how can I make the whole div to act as a link - when you click anywhere on that div, to take you to an address.

The "a:hover" literally tells the browser to change the properties for the <a>-tag, when the mouse is hovered over it. What you perhaps meant was "the div:hover" instead, which would trigger when the div was chosen.

Just to make sure, if you want to change only one particular div, give it an id ("<div id='something'>") and use the CSS "#something:hover {...}" instead. If you want to edit a group of divs, make them into a class ("<div class='else'>") and use the CSS ".else {...}" in this case (note the period before the class' name!)

Using 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>