Appearance
Theme and window transparency live in Settings > General. The Settings UI writes personal settings.json. Keys and defaults are on settings.json.
The same Settings section also has a shortcuts list and the GitHub Releases updater. See Shortcuts and the command palette and Installation.
Theme
Choose Light, Dark, or System. The default is System. The title-bar control toggles Light and Dark only (not System) and writes the same appearance.theme key.
Transparency
Turn Enabled on to tint the window (appearance.transparency, default on). Hue runs 0 to 360 (default 265). Intensity runs 0 to 100 (default 0). The preview updates while you drag the sliders.
These keys are appearance.transparencyHue and appearance.transparencyIntensity.