Docs / linux / theme / README.md

#Linux theme files

light/<id>.css and dark/<id>.css redefine libadwaita's named colours (accent_bg_color, window_bg_color, view_bg_color, sidebar_bg_color, card_bg_color …) plus sub_* role colours.

Defaults: light/moss-paper.css and dark/forest-floor.css.

How to apply them:

1. Bundle both folders in the GResource as /com/substratalapps/Hub/theme/.
2. Keep one Gtk.CssProvider at GTK_STYLE_PROVIDER_PRIORITY_APPLICATION.
3. On startup, and on every notify::dark from AdwStyleManager, load {dark ? dark/<dark_theme> : light/<light_theme>}.css into that provider.
4. Map Settings.theme to AdwStyleManager:color-scheme:
   • light → FORCE_LIGHT
   • dark → FORCE_DARK
   • system → PREFER_LIGHT, which follows the system setting
5. When AdwStyleManager:high-contrast is true, do not load a theme file, so the system's high-contrast palette applies.

let provider = gtk::CssProvider::new();
gtk::style_context_add_provider_for_display(&display, &provider, gtk::STYLE_PROVIDER_PRIORITY_APPLICATION);
let apply = move |sm: &adw::StyleManager| {
    if sm.is_high_contrast() { provider.load_from_string(""); return; }
    let path = if sm.is_dark() { format!("/com/substratalapps/Hub/theme/dark/{}.css", dark_id) }
               else { format!("/com/substratalapps/Hub/theme/light/{}.css", light_id) };
    provider.load_from_resource(&path);
};