I need to stretch my banner Image at the top of the page to the whole of the page. The development computer on which I was working for this site displayed it correctly.

Today when I opened the code in another compter the top banner image didn't display itself for the whole of the page. It just contracted to the left side. I am wondering how do do it.

well I used background-image:100% but that didn't work(CSS3 compatibility issues).

Anytips to stretch this top banner to the whole of the page in every computer is welcome