/* foo.css */
.foo {
    color: red;
}

// foo.css.js
(function () {
    var cssText = ".foo {\n" +
                  "    color:red;\n" +
                  "}";
    // some DOM script to inline style element
}());

grunt.loadNpmTasks('grunt-css2js');

grunt.initConfig({
    ...
    css2js: {
        foo: {
            src: 'src/foo.css',
            dest: 'dist/foo.css.js'
        },
        bar: {
            src: [ 'src/bar/a.css', 'src/bar/b.css' ],
            dest: 'dist/bar.css.js'
        }
    }
    ...
});