One of the biggest issues I’ve noticed personally with Firefox is that it offers a less consistent rendering across the other browsers. It has been several years since I have last used it, so maybe it has improved and I’m just ignorant to it.

In the past, I noticed that I would end up writing bulkier CSS code to get the UI to render correctly in Firefox and that specificity would result in rendering issues with other more W3-compliant browsers. I would either have to go back and clean/rewrite a lot of my CSS, or end up including a bunch of hacky !important tags on additional CSS to backtrack on some of the overly-specific styles I wrote for Firefox.

I find, especially when I use Chrome, that I write lighter CSS and I only end up having to make a few browser-specific tweaks once I get to my cross-browser compatibility checks. Furthermore, once you familiarize yourself with browser prefixes, you’ll notice that it is easiest to directly target IE, Mozilla, and Opera than it is to target Chrome or Safari.