I would also suggest box-sizing, and knowing the difference between the values, and when they're needed. Further, there's value in considering a border-sizing global reset. That said, as with JS, CSS is very fiddly, and there are dozens, if not hundreds, of different ways to achieve a visually similar result.
Some comments have been hidden by the post's author - find out more
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.