The title bar on Linux does not render properly using a dark theme

[carotteatomique]

Bug Description

On Linux, the title bar for FluffyChat has really low contrast with the text when using a DE's dark theme, making it pretty hard to read. This affects both the text and the window decorations (close, minimize, etc.)

The text is slightly more legible when the window is unfocused.

It seems that FluffyChat does not change the color of the text and window decorations when changing from light mode to dark mode, which would explain the poor contrast in dark mode.

Steps to Reproduce

1. Set your desktop environment to use a dark theme
2. Open FluffyChat
3. Click on FluffyChat to have it focused
4. Observe the lack of contrast

Expected Behavior

For the FluffyChat titlebar to have better contrast, ideally by using the default title bar provided by the DE, since FluffyChat does not seem to use it's title bar in a special way.

App Version

1.22.0 Flathub version, running natively on Wayland

Additional Platform Information

Laptop running Fedora 41 with KDE Plasma 6.2.2

Additional Context

The screenshot attached is from KDE Plasma 6.2.2 running on Fedora 41, but I also tested the app on Gnome 47 running on Gnome OS, and the same bug happens. Although the window decorations are different, they still have very poor contrast.

I have also tested the Snap package on the same Fedora KDE machine, and it seems that it has the opposite problem: the text is well contrasted when using a dark theme, but completely illegible using a light theme.

[carotteatomique]

If my memory is correct, this bug was introduced in version 1.22.0. Before, the title bar would be white (and have good contrast) no matter the theme.