Call reaction stack

Up to three timed reactions per person in one centred row: one in the centre, two as a centred pair, three left to right in arrival order. When the count changes they slide to their new places. Each leaves 4.5 s after it arrived; a fourth joins at the right end and the oldest fades out where it was. Below 240 px a tile scales its reactions to 20% of its width. The name pill paints on top.