Hacker News Reader

I think that's referring to screen width. As in, breakpoint for when screen witdth is >= 1536px and as screens use pixels, that is the only unit talking about screens is reasonable in. em/rem/whatever don't make sense in media queries.

I see, thanks y'all.

Most people use rem these days, but there are common browser bugs with using rems or ems in media query rules, so in the rules specifically it is common to still specify pixels, even if the rest of your stylesheet uses rems or ems.

Pixels have always had their uses, but I moved from em to pixels even for sizes that would ideally scale with text in order to be able to get things to align to whole vertical pixels (and horizontal ones, when not centered).

px is still easier and more convenient to reason with, plus it's more readable. I use px in my code but I also use a postcss plugin to convert them to rem during build time

Also the magnificent rem (root em) unit.