My grid collapsed at 2am on a Tuesday because I forgot a single minmax and the fix was one line
I was sitting in my kitchen in Dayton staring at a product page where all 9 cards had squished into a weird pile because I had written `repeat(3, 1fr)` with no floor on the column width, and swapping it to `repeat(auto-fit, minmax(220px, 1fr))` fixed the whole mess in about four seconds, so now I want to know: what is the one property you keep forgetting that turns a working layout into soup?