High contrast doesn't work in catalogs

[kyrosene]

Describe the bug GNOME's high contrast accessibility mode doesn't apply to the catalog pages in Foliate, while it applies to the rest of the interface

To Reproduce Steps to reproduce the behavior:

1. Enable high contrast mode in system settings
2. Go to one of the catalog pages in Foliate
3. Compare with high contrast mode off

Expected behavior Elements would have higher contrast, like white outlines

Screenshots Screencast from 2024-02-08 23-58-35.webm

Version:

• Foliate version: 3.1.0
• OS/Distribution and version: Fedora 39
• Desktop environment: GNOME 45.3
• Installation method: Flatpak

[johnfactotum]

There's no high contrast mode for the footnote dialog, either. And also the header/footer.

Would be nice if WebKitGTK could support prefers-contrast. It's apparently supported by Safari but not in the GTK port yet.

Of course it can, and probably should, just read the setting from the StyleManager in Libadwaita. The main reason I haven't done that yet is that signals are annoying to work with.