It seems that the background-fixed CSS property doesn't work right in Jelly Bean WebView (both inside an application and using the default Android browser).
If I set this property, the background image gets loaded over the content, i.e. the content is behind the background image.
Here's my relevant HTML code:
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">   
<meta name="viewport" content="target-densitydpi=device-dpi">
<meta name="viewport" content="initial-scale=1.0">
<link rel="stylesheet" type="text/css" href="./gesture-background_files/genre-channel-background.css">
<style type="text/css"></style></head>
<body>
<div id="right-keys">
    <a href="keypress://1"><img src="./gesture-background_files/one.png"></a><br />
    Film24<br />                    
</div>
<div id="right-keys-vertical">
    <a href="keypress://1"><img src="./gesture-background_files/one.png"></a><br />
    Film24<br />
</div>
<div id="footer">
    MUSCADE<span class="large">EPG</span>
</div>   
</body>
</html>
And here's the relevant part of the CSS:
body {
    background-image: url(hot-black-background.jpg);
    background-color: black;
    background-repeat: no-repeat;
    background-attachment: fixed;
    background-position: bottom left;
}
#right-keys, #right-keys-vertical {
    position: absolute;
    right: 10px;
    width: 100px;
    text-align: center;
    text-shadow: black 2px 2px 0px;
}
#right-keys img, #right-keys-vertical img {
    height: 90px;
    margin-bottom: 0;
}
#footer {
    position: absolute;
    right: 10px;
    bottom: 10px;
    font-size: 20px;
}
It's a bit long, but the only important part are the background-attachment and background-position properties on top of the CSS file. If I remove those, everything works fine.
Is this a known bug? Can anyone suggest a workaround?
Here's a link to the file so you can try opening it from a Jelly Bean native browser (not Chrome):
http://212.92.197.78/gesture/gesture-background.htm