utils.js

 exports.cssLoaders = function(options) {
    options = options || {}
    // generate loader string to be used with extract text plugin
    function generateLoaders (loaders) {
        var sourceLoader = loaders.map(function (loader) {
            var extraParamChar
            if (/\?/.test(loader)) {
                loader = loader.replace(/\?/, '-loader?')
                extraParamChar = '&'
            } else {
                loader = loader + '-loader'
                extraParamChar = '?'
            }
            return loader + (options.sourceMap ? extraParamChar + 'sourceMap' : '')
        }).join('!')

        if (options.extract) {
            return ExtractTextPlugin.extract('vue-style-loader', sourceLoader)
        } else {
            return ['vue-style-loader', sourceLoader].join('!')
        }
    }

    // http://vuejs.github.io/vue-loader/configurations/extract-css.html
    return {
        css: generateLoaders(['css']),
        postcss: generateLoaders(['css']),
        less: generateLoaders(['css', 'less']),
        sass: generateLoaders(['css', 'sass?indentedSyntax']),
        scss: generateLoaders(['css', 'sass']),
        stylus: generateLoaders(['css', 'stylus']),
        styl: generateLoaders(['css', 'stylus'])
    }
};