private final HtmlColor getBackColor() {
		if (EntityUtils.groupRoot(group)) {
			return null;
		}
		final HtmlColor result = group.getSpecificBackColor();
		if (result != null) {
			return result;
		}
		final Stereotype stereo = group.getStereotype();
		final USymbol sym = group.getUSymbol() == null ? USymbol.PACKAGE : group.getUSymbol();
		final ColorParam backparam = sym.getColorParamBack();
		final HtmlColor c1 = skinParam.getHtmlColor(backparam, stereo, false);
		if (c1 != null) {
			return c1;
		}
		if (parent == null) {
			return null;
		}
		return parent.getBackColor();
	}