Layout utilities wrap single properties from Box Model Properties (absolute is position: absolute), and three naming patterns make most class names guessable:
Keyword utilities map to a value: block, sticky, isolate.
Scale utilities multiply a number by the --spacing theme variable (0.25rem), so top-4 is top: calc(var(--spacing) * 4), or 1rem. Fractions are percentages (left-1/2), full is 100%, and a leading - negates (-top-2).
Escape hatches: [value] for any literal (top-[3px], z-[60]) and (--name) for a custom property (z-(--layer-modal)).
All accept the variants of Core Concepts, as in hidden md:block.