def rel_to_abs(self, base_url):
        """
        Converts relative links from css contents to absolute links

        :param base_url: The base page url to use for building absolute links
        :type base_url: str
        :param css_contents: The CSS contents to parse
        :type css_contents: str
        """
        self.cleaned_css = self.rel_to_abs_re.sub(
            lambda match: "url('%s')" % urljoin(
                base_url, match.group('path').strip('\'"')),
            self.cleaned_css)
Converts relative links from css contents to absolute links

        :param base_url: The base page url to use for building absolute links
        :type base_url: str
        :param css_contents: The CSS contents to parse
        :type css_contents: str