fix(umbriel): reduce wallpaper bleed through translucent browsers

dot_config/umbriel/rules.toml

@@ -48,6 +48,12 @@ opacity = 0.9
 default_floating = false
 default_focused = true
 
+# Browsers: web pages are mostly light backgrounds and text, so 0.9 lets too
+# much wallpaper through. Nearly opaque; after the rule above, so it wins.
+[[window_rule]]
+match.app_id = ["^brave-origin$", "^zen$", "^chromium$"]
+opacity = 0.97
+
 # ==============================================================================
 # Floating utilities