Vent: I wasted a year hard-coding every media query by pixel before I learned about clamp()
For about two years I built every responsive font size by hand, writing out something like four or five @media blocks per text element, one at 480px, one at 768px, one at 1024px, and so on. I thought that was just how it worked. Then a guy I follow posted a 3 line snippet using clamp() and my jaw dropped. One line did what took me 15 lines of breakpoints before. I switched my whole stylesheet over about six months ago and my CSS went from around 900 lines down to maybe 400. It also fixed a bunch of "in between" sizes that used to jump ugly. What's the one CSS function you slept on way too long before trying it?