Description: http://ha.ckers.org/xss.html#XSS_STYLE_background-image
Options: -style, -safe_attrs_only
Notes: The CSS is messed up here, but so it goes

<div><STYLE>.XSS{background-image:url("javascript:alert('XSS')");}</STYLE><A CLASS=XSS></A></div>
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<div><style>.XSS{background-image:url("");}</style><a class="XSS"></a></div>