FractionalGui
Attention for users of version 1.21.6 and above: Mojang has changed the internal representation of GUI scale from a double to an integer, which makes the method used by FractionalGui no longer work. Updates are temporarily suspended until a solution is found or the mod is archived.
FractionalGui is a simple addon that expands GUI scale customization options by offering intermediate values between standard settings.
Important warning: This mod is experimental and may work unstable. Various graphical artifacts and incorrect display of interface elements are possible.
Currently, there are no plans to add anti-aliasing for user interface elements. However, if you have ideas for implementing this feature - you can suggest your solutions.