code: function _replaceCssRelativeUrls (data, baseFileUrl, imports) {
  		var url = baseFileUrl.replace(/\\/g, "/"),
  			lastSlash = url.lastIndexOf("/"),
  			baseUrl = lastSlash >= 0 ? url.slice(0, lastSlash + 1) : "";
  
  		return data.replace(
  			/url\(\s*(['"]?)((http:\/\/|https:\/\/|\/)?[^'"\s]*)\1\s*\)/g,
  			function (text, quotes, url, prefix) {
  				// do nothing for absolute urls
  				if (prefix) { return text; }
  				return "url(" + baseUrl + url + ")";
  			}
  		).replace(
  			/@import\s+(['"])((http:\/\/|https:\/\/|\/)?[^'"\s]*)\1\s*;?/g,
  			function (text, quotes, url, prefix) {
  				if (imports) {
  					imports.push(baseUrl + url);
  				}
  				// return special stub which will be replaced by imported css-file later
  				return "/*>>import: " + baseUrl + url + "*/";
  			}
  		);
  	}
docs: Replaces relative links in content of css-file onto links which are relative to the specified url (baseFileUrl).
  Also stripped out all @import directives.
  @param data Content of css file
  @param baseFileUrl base URL for new relative links
  @param {Array} [imports] an array where all @import urls will be added to
  @returns {String} new content of css file