I was really only able to find two OLED-firendly portable freeware tools:
- Notepad++ via the style configurator
- Firefox - https://addons.mozilla.org/en-US/firefo ... ust-black/
- Easy Invert - if you have mostly white windows (by the developer of System Font Size Changer, which Ennovy highlighted last year)
Related: OLED desktop backgrounds (some of these are excellent): https://www.reddit.com/r/Amoledbackgrounds/