title: How to stretch a background image to a fill a div
body: <p>I want to add a cover image to my web site. I have a div tag in the top of the page. I have set the div tag's width to 80% and height to auto. I want add an image as the background of that div. That image width should stretch according to the width of the div. Image height should changed automatically according it's new width (stretched width).</p>