I experienced the same issues. I had to restart my portfolio a couple of times because the more I tried to fix the problem, the more I struggled and messed up my code to such an extent that it was best to just start from scratch again.
I finally realised I had to check everything I do, as I do it, in all the browsers I use to check compatibility. There are still some minor differences between the browsers that frustrate me as I like things to be
perfect, but I've come to grips with the fact that I am still too much of a novice to sort these things out faster and I can't keep starting from scratch all the time.
That said, I'm not sure whether it's at all possible to have your website display exactly the same in all browsers.