code: public void addCssResource(final ApplicationResource resource) {
  		WApplicationModel model = getOrCreateComponentModel();
  		if (model.cssResources == null) {
  			model.cssResources = new ArrayList<>();
  		} else if (model.cssResources.contains(resource)) {
  			return;
  		}
  		model.cssResources.add(resource);
  		MemoryUtil.checkSize(model.cssResources.size(), this.getClass().getSimpleName());
  	}
docs: Add a custom CSS resource that will be loaded and used by this application.
  
  @param resource the CSS resource