No offense author, but what is specifically ADHD related in this timer? Actually I'd argue that it is ADHD unfriendly because it is in the web browser. So now I need to open a browser and hunt down one tab among hundreds, because as a ADHD person I tend to hoard them to process later and of course never do it.

There are also no notifications or sounds in your website (I may have nuked all browser notifications at some point, to combat asshole webdesign, and now I have no idea if that's a default setting).

The 100% expected scenario of how ADHD person would use your timer is open it, set up a timer, check it periodically if it has finished or not, happily get to first break, then setup second work period, forget about timer until 3 days later, and find it when cleaning up open tab. Close it forever. Source - this would be a fifth or so exact same pomodoro "app"-website I've tried and abandoned.