Portlets rely on different URL semantics than normal web applications. The way we handle this in our theme.css file is to use the 'resource' expression language tactic. Since CSS files are processed for EL, you can specify resources in a way that makes them work whether they are installed as a plain application or a portlet (as the PortletFaces Bridge now gets to help construct the appropriate URL for the portlet container). So in the theme.css files we see URLs that are constructed as follows:

 url("#{resource['icefaces.ace:themes/rime/images/ui-bg_inset-hard_100_eeeeee_1x100.png']}"

The CSS files that we include with the showcase example use "raw" URLs. For example, in showcase_styles.css we have:

.ice-checkboxbutton .ui-state-active {
    background: url("/resources/css/images/success24.png") no-repeat;
    border: 1px;
    border-style: solid;
}

Unfortunately, if the resource location is not done correctly, it won't work properly in both environments. It would be better to adjust them as follow:

.ice-checkboxbutton .ui-state-active {
    background: url("#{resource['css/images/success24.png']}") no-repeat;
    border: 1px;
    border-style: solid;
}