Where are you putting the div element (in your header.php I presume)? I am trying to do the same thing – get full width backgrounds for non-compliant browsers. CSS3 works fine in FF10, but not Chrome or IE8.
My problem is I cannot get the image to display at all – I have been putting the div in the header.php at the very start of body definition, i.e.
…
</head>
<body <?php body_class(); ?>>
<div id=”dImgBg”>
<img src=”images/bgTmp.jpg” id=”bgImg”/>
</div>
<div id=”page” class=”hfeed”>
…
I have had no issues with the footer.
