@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); @namespace html url("http://www.w3.org/1999/xhtml"); html|canvas#screen { margin: 12px 11px 32px; } #monitor { list-style-image: url("chrome://browser/skin/monitor.png"); } #monitor[aspectratio="16:10"] { list-style-image: url("chrome://browser/skin/monitor_16-10.png"); }