Noise Machine
White, pink, brown, blue, violet and grey, generated rather than approximated, with rain, wind, surf, a fire and six more beds to lay over them. Nothing loops, so it sounds the same at six in the morning as it did when you started.
Presets
Levels
Sleep
Beds
Shaping
This browser has no AudioWorklet, so the machine cannot run here. Everything on the page is generated a sample at a time and there is no recording to fall back on.
The fade out is the last part of the sleep timer, not extra time on the end, and it runs down in decibels rather than in amplitude. Both fades are scheduled on the audio clock, so a phone that stops giving the page timers cannot leave it playing.
Every setting lives in the address, so the link in your bar is the machine as it stands. The last state comes back on its own next time.