Who needs resource packs or texture packs, with Let There Be Dark, you can toggle between a dark and light mode without the need of reloading a resource pack.

Images:

Title Screen Dark Mode:

!Title Screen Dark Mode:

Config using Cloth Config:

!Config

Dependencies:

• Fabric API (1.21.4+)
• Cloth Config API (1.21.4+)
• Mod Menu (1.21.4+) Optional as of version 1.3.2

These can also been found in the versions tab.

Features:

This not only works with UI elements like buttons or sliders, but also GUI elements like the inventory screen. A customizable keybind (default F10), can be used to change the mode in-game, so you can have a seamless experience and a simple config screen for easy customization. Im my opinion, this mod looks best in 1.21.4 and 1.21.5, after 1.21.6, Mojang changed the rendering engine, so the dark effect won't look as good, but it's still decent.