Sometimes, it is really hard to tell if a responsive theme can really work on all different platforms or not. One simple way to test your theme’s responsiveness is to use an online emulator service such as BrowserStack.
BrowserStack allows users test their websites on different browsers and operating systems. One might find it extremely invaluable since most people likely don’t have access to computers running all different kinds of OS and browsers. If you are interested, you can create a trial account which gives you some free live testing time and screenshots. Can you trust the result entirely? Well, my word of advice is that if possible you might still want to test your site on any real devices you can get your hands on. 🙂