After leveling up on typography and what it takes to define a nice typographic grid I found REMs to be a revelation. A key concept of good typographic grid des

After leveling up on typography and what it takes to define a nice typographic grid I found REMs to be a revelation. A key concept of good typographic grid design is that the body copy line height (or font size as a proxy) is a very important measurement to be reused across your grid. TLDR; By using your body font size as a basic unit of measure for other visible distances eg padding, margins it's possibly to make your design look better and feel more unified. My crude rule of thumb for beginners is to use REM for everything by default and then change over to EM anywhere this is not working for you (and this is a crude summary of key advice in this article) One style guide I read suggested that pixels were ok for anything up to 5px and that REM/EM should always be used otherwise (towards ensuring a nice typographic grid) and I think that's a good practical approach. If you're essentially thinking in REMs and just translating that to px in certain circumstances to get around crazy numbers, great,if that works for you. But I think that generally REMs provide free design benefits for those that switch to them rather than adding arbitrary non-proportional pixels lengths everywhere within a design.