[dtran]

Awesome project! Reminds me of donothingfor2minutes.com from Calm, but with a different end goal of focus instead of calm.

Regarding mobile phones going to sleep, Wake lock [1] might help, unless you can reduce to 59s since I believe 1m is the threshold (make sure to request within the context of the user hitting "start"). Unfortunately on older mobile browsers [2], the best workaround I found was using this NoSleep library[3].

Source: ran into this same issue when building https://www.phonefreehour.com

[1] https://developer.mozilla.org/en-US/docs/Web/API/WakeLock

[2] https://caniuse.com/wake-lock

[3] https://github.com/richtr/NoSleep.js