test

            std::string ref = (start == std::string::npos) ? ""

                             : inner.substr(start, end - start + 1);

            char quote = '\0';

            // Detect either quote style, but always re-emit with single

            // quotes regardless of which one the original used -- this text

            // can end up set as an HTML "style" attribute value (see

            // rewriteRelativeUrls), and libhtmlpp::HtmlElement::setAttribute

            // throws on ANY literal '"' in an attribute value (it has no

            // escaping, just an outright reject) -- so a double-quoted

            // url("...") re-emitted verbatim would crash the import outright.

            bool quoted = false;

            if (ref.size() >= 2 && (ref.front() == '"' || ref.front() == '\'') &&

                ref.back() == ref.front()) {

                quote = ref.front();

                quoted = true;

                ref = ref.substr(1, ref.size() - 2);

            }

            out += "url(";

            if (quote) out += quote;

            if (quoted) out += '\'';

            out += fn(ref);

            if (quote) out += quote;

            if (quoted) out += '\'';

            out += ')';

            i = close + 1;

        } else if (ciMatch(i, "@import")) {