Your app builds its whole UI in code, every frame. The library does the rest:

It keeps the state between frames:
- focus
- scroll positions
- open menus
- window rects
It lays the UI out with flexbox and grid.
It handles input.
It draws the UI.

Everything is in the tachyon namespace. Examples are written as members of a class derived from GUIApplication, like the one in the README.

Then: Controls, CSS and theming, or Integration to host the library in an existing application.

Page	Covers
The application and the frame	GUIApplication, OnGUI, the steps of a frame
IDs	Call-site, static and ranged IDs, parent scopes, when an ID must be stable
Begin and End	Pairing Begin* with End*, scope objects, misuse
Return values, content and units	Return values, callbacks, GUIContent, CSS px versus pixels
Errors and saved state	Result<T>, error codes, saving window and dock layouts