SySafarila/stream-overlays ? reverse-engineered prompt

Build me a simple customizable stream overlay for donations that works with saweria.co and bagibagi.co.

I want a page where I can fill in the needed settings, save the setup, then copy the generated URL into OBS as a Browser source. It should be made for a stream overlay workflow, so the finished page should look good on screen, fit a width of 425 and height of 800, and not need any custom CSS in OBS. Please make it easy for a streamer to open the config page, enter their info, save it, and test a donation from their dashboard to see the alert appear. If you need to check current docs or details for saweria or bagibagi, look them up online first.