There are a bunch more interesting ones that folks often haven't heard of, like ex (relative to the height of an x) or ch (relative to the width of a 0) https:

There are a bunch more interesting ones that folks often haven't heard of, like ex (relative to the height of an x) or ch (relative to the width of a 0) https://developer.mozilla.org/en-US/docs/Web/CSS/length https://developer.mozilla.org/en-US/docs/Web/CSS/length (not all of the ones in that page are implemented by browsers, e.g. I don't think anyone implements `cap` or `ic` since it's from a draft spec)