Deathbyteacup/fluentbird: FluentBird is a userChrome.css theme for Mozilla Thunderbird, that implemenets Windows 11 Fluent Design and Mica transparency materials.

FluentBird is a userChrome.css theme that brings Windows 11 Fluent Design and Mica transparency effects to Mozilla Thunderbird. The theme supports both dark and light modes, requires enabling userChrome.css and specific Mica flags in Thunderbird's configuration, and works best on Windows 11 systems. Currently in beta version 0.1.5, it provides comprehensive theming for the mail interface while having limitations in certain areas like settings and popup windows due to Shadow DOM restrictions.