[Feature Request] Add accent color CSS property

[maicol07]

Is your feature request related to a problem? Please describe. Accent color in a CSS property so themes can use it.

Describe the solution you'd like A CSS property that stores the accent color value and updates it when it changes.

Describe alternatives you've considered Manual accent color via CSS

Additional context BetterDiscord implementation: https://github.com/BetterDiscord/BetterDiscord/pull/1663 Tauri idea: https://github.com/tauri-apps/tauri/discussions/5305