How to make outer div has the same submit behavior as its content asp.net button

[trigga]

I have a div with rounded corners in asp.net form, it contains a "submit" which is written in asp.net button.The four corners are not clickable and don't have the same behavior as "submit" button. How can i do to make the whole div clickable and have the same behavior as clicking the button?Any ideas are welcome.\[code\]<div><a><span><input type="submit" onclick="javascript:WebForm_DoPostBackWithOptions....etc" value="http://stackoverflow.com/questions/12693974/Valider" name=""></span></a></div>\[/code\]Thanks.