jodd-htmlstapler/src/main/java/jodd/htmlstapler/HtmlStaplerBundlesManager.java
protected String fixCssRelativeUrls(final String content, final String src) {
		final String path = FileNameUtil.getPath(src);

		final Matcher matcher = CSS_URL_PATTERN.matcher(content);

		final StringBuilder sb = new StringBuilder(content.length());

		int start = 0;

		while (matcher.find()) {
			sb.append(content, start, matcher.start());

			final String matchedUrl = StringUtil.removeChars(matcher.group(1), "'\"");

			final String url;
			if (matchedUrl.startsWith("https://") || matchedUrl.startsWith("http://") || matchedUrl.startsWith("data:")) {
				url = "url('" + matchedUrl + "')";
			}
			else {
				url = fixRelativeUrl(matchedUrl, path);
			}

			sb.append(url);

			start = matcher.end();
		}

		sb.append(content.substring(start));

		return sb.toString();
	}
protected String fixCssRelativeUrls(final String content, final String src) {
		final String path = FileNameUtil.getPath(src);

		final Matcher matcher = CSS_URL_PATTERN.matcher(content);

		final StringBuilder sb = new StringBuilder(content.length());

		int start = 0;

		while (matcher.find()) {
			sb.append(content, start, matcher.start());

			final String matchedUrl = StringUtil.removeChars(matcher.group(1), "'\"");

			final String url;
			if (matchedUrl.startsWith("https://") || matchedUrl.startsWith("http://") || matchedUrl.startsWith("data:")) {
				url = "url('" + matchedUrl + "')";
			}
			else {
				url = fixRelativeUrl(matchedUrl, path);
			}

			sb.append(url);

			start = matcher.end();
		}

		sb.append(content.substring(start));

		return sb.toString();
	}
Returns the content with all relative URLs fixed.