By the way, I used to use tools like Browser Stack, but nowadays there aren’t enough differences with the view. I just test in Chrome. Near the end of the project I load Firefox and Safari, and a couple of mobile phones with whatever they have installed. Nothing else, nothing old. That’s because I work alone, if you have a team, you are part of a big company or you make open source stuff, you should make the right tests.
Using frameworks helps a lot to reduce those differences (if you know how to use them).