Today, it's a really quick one. I came across the
ex unit in CSS, and I didn't know that it was a thing. It stands for the
x-height, and the spec defines it as follows:
The x-height is so called because it is often equal to the height of the lowercase "x".
I'm not sure when I would use that, but I hope to remember it when I find a need for it. A picture is worth more than words, so here we go with a quick #devsheets illustration. 👇