Layout testing seemed always a complex task. Galen Framework offers a simple solution: test location of objects relatively to each other on page. Using a special syntax and comprehensive rules you can describe any layout you can imagine.
Galen Framework runs well in Selenium Grid. You can set up your tests to run in a cloud like Sauce Labs or BrowserStack so that you can even test your responsive websites on different mobile devices. Galen can run multiple tests in parallel which is also a nice time saver.
Galen Framework is designed with responsivness in mind. It is easy to set up a test for different browser sizes. Galen just opens a browser, resizes it to a defined size and then tests the page according to specifications.