Checkout Stepper

Where the shopper is in checkout: a rail of equal ruled cells, edge to edge. Done steps carry a check and are buttons back to them; the current step is aria-current="step"; steps to come are not clickable. Never colour alone — a check, a number, and a heavy rule under the current step that slides on as the shopper moves (Motion; a fade under reduced motion). On a phone the rail shows numbers, with the step named below it.