Mahjong on a phone
Built for a fingertip: tiles do not jump around, the board fits the screen, and it can live on your home screen like an app.
Tile size
On a 375-pixel screen the Tower tiles are about 44 pixels — easy to hit. In Turtle they shrink to roughly 20, which is why rotating the phone helps.
Rotation
Portrait gives height, landscape gives width. On the big board landscape is better: tiles grow almost twice.
Installing
Add the site to your home screen and it opens without an address bar, fully offline. On iPhone that is Share → Add to Home Screen; on Android, the Chrome menu → Add to Home screen.