CSS is not wiping the page overnight. The quiet stretch is. Seven months in, you already ran align-items and centered the div. What goes soft is which knob does what once a layout sits untouched for three weeks. Vocab cards work for anatomy because the fact stays one shape. Flexbox changes the second the parent gets a new width, so rereading MDN feels brand new even when the moves are still in there. A blank file and the same three patterns, center, space-between, wrap, sticks better than another pass at the docs.