Yes, so good. Thanks!

I apologize, but contrast of activet tab is still too low for me (in 3.6.17052 pre-release). Would it be possible to add the ActiveTabBackgroundColor and ActiveTabForegroundColor parameters to the advanced settings? Or just the InvertActiveTabColor parameter? Thank You.

@username116
SumatraPDF has had an "experimental" background feature as long as I can remember so you chose what you want within reason

one to three colours based on GradientColors = #ff0000 #0000FF after FixedPageUI [

@username116 done in https://github.com/sumatrapdfreader/sumatrapdf/commits/master, will be in next pre-release build

Thank you very much for your answers.

@GitHubRulesOK I hadn't tried this setting. I tried it, and indeed I can set the background color I want, even in dark mode. Thanks for the tip.

@kjk thanks, I look forward to the next pre-release.

Idea: indicate in the advanced settings help of the next version, for TextColor, BackgroundColor and MainWindowBackground settings, that these settings don't work with dark themes. And for MainWindowBackground, that GradientColors can be used instead for a setting with dark theme.
This could save time for people like me trying to adjust the dark theme colors.

Here's the result and how it compares with the previous version.

I don't see any difference with the light theme on my screenshots (although the code 98b86d6 also changes the lightness with the light theme?).
I would have set -8 instead of +8 with the dark theme, to darken the background of the document a little, instead of lightening it. With the text which is already a little greyed out, it lacks contrast in my eyes. But I got what I wanted, the edges of the sheet are visible. Thanks for the change.

If you look at at GetDocumentColors() it treats the light theme in a special way so this code won't execute which is why the light theme didn't change.