textbrowser
textbrowser
This a solvable through a modern Linux distribution as some include Night Lights and environment adaptability and sometimes darkness forever mode. So here's what you have. https://doc.qt.io/qt-6/qtwebengine-features.html
If you see a mechanism there, we consider. If not, it'll be a non-portable, non-fantastic solution of toying with colors and alphas and maybe transparencies and highlight and lowlight and...
Meanwhile there are inexpensive glasses which dim life for you. Or timely pauses in computing activities. Yah.
WebEngine does not include a means of accessing a page's scrollbars. One needs JS for scrolling in that world. Chat is glue-less.
GPT believes JS would solve the problem in WebEngine?
GPT is wrong with 100% confidence of being correct with itself. Is non-artificially ignorant.

Happy you are?
Is dark mode. And available in right now. See Settings. There may be a means of offsetting colors but I do not know of it and it requires special focus...
The thing you have pictured is like a thin sheet of somewhat-transparent paper over the document. So a background color adjustment would not work. You need a mask on the...