Ergonomic decisions on this page

• Big buttons. +1 buttons are 140px tall, thumb-sized for a phone in portrait, gloved-finger safe.
• Undo is huge. One mistap during a scoring storm shouldn't require navigation to fix.
• Leading team gets visual prominence. Color-mix on the column background tells you who's winning in a glance.
• Set tally on each side. Won sets as gold cells, current set highlighted. No "what set is this" cognitive load.
• Offline banner is canonical. When network drops, the banner appears and queued count shows. Tap +1 still works — increments sync on reconnect.
• Mono everywhere data lives. Court, set, score — all monospaced. Reads as data, not text.
• No nav, no menu, no settings. Scorekeeper has one job. Get out of their way.