FOUNDATIONS
The primitives everything else is built from.
Checkpoints' visual language is unusually constrained: no rounded corners, a pixel typeface, a single icon family, and a palette that has to hold up across twelve wildly different themes. These are the rules that make that work.
Color & themes
Roughly 50 custom properties per theme, twelve themes deep. How the palette is structured and why --action exists alongside --primary.
Typography
GeistPixel Square for headers, JetBrains Mono for everything else — and the themes that override both.
Spacing & shape
Tailwind's 4px scale, and why zero radius turns out to be the default rather than the rule.
Iconography
One pixel icon family, 4,111 glyphs, two rendering strategies — one of which is a bug waiting to happen.