Unfortunately with macOS's "Dark Mode" enabled the colors have little or no contrast. And the UI renders very small for my eyes (and compared to the demo gif). This is a criticism of Qt (or maybe its python bindings) rather than this project. (Screenshot: https://imgur.com/a/G9eAPoO)
I wonder if there's a way to shimmy in a "modern macOS Qt renderer" or something into an existing project like this without a rewrite?
Apparently there is. I hacked something together in a new branch: https://github.com/fellerts/procal/tree/fredrik/theme. Feel free to check it out and let me know how it works for you.
QFont('Monaco', 12)
Edit: merged a fix for this, thanks for reporting.
But in my experience with Qt, you always have to adjust font names separately for every OS. This is especially true for nice coding fonts.
If I had written that program, I would have brought my own font (like "Hack"), and simply set the pixel size of the font, to ensure it's exactly the same size on any OS (and I would have written it in QML, with heavy usage of Repeater, which would simplify the UI code a lot, but I digress...).
You could play with the QT_SCALE_FACTOR environment variable to fix the scaling issue at least. Something like this could work:
$ QT_SCALE_FACTOR=2 python procal.py