// build the url function
CssFunctionNode urlFunction = new CssFunctionNode(Function.byName("url"), location);
CssDotPathNode imageUrl = new CssDotPathNode(resourceThisPrefix, imageResource + ".getSafeUri" +
".asString", null, null, location);
CssFunctionArgumentsNode urlFunctionArguments = new CssFunctionArgumentsNode();
urlFunctionArguments.addChildToBack(imageUrl);
urlFunction.setArguments(urlFunctionArguments);
// build left offset
CssDotPathNode left = new CssDotPathNode(resourceThisPrefix, imageResource + ".getLeft", "-",
"px", location);