If you debug and edit your CSS in the WebKit Web Inspector, **CMD+Z will undo your last change.** (CTRL+Z for my Windows friends.)\r\n\r\nSimilarly, **CMD+SHIFT+Z is redo.** (CTRL+SHIFT+Z in Windows.)\r\n\r\nIn addition to fixing up a mistake, this also works well as a quick toggle for visually comparing style variations.