layout
8pt grid
A spacing discipline where every margin, padding and gap is a multiple of 8px (with 4px as a permitted half-step for tight spots).
Instead of eyeballing “does this look about right”, pick one small number and make every space a multiple of it. Spacing that steps 8, 16, 24, 32 reads as considered; spacing that steps 7, 13, 22, 31 reads as off – even to people who can’t say why.
Why 8 specifically: it halves cleanly (4, 2) so small components can step down gracefully, and common screen densities scale cleanly from an 8px base, avoiding blurry sub-pixel rendering. But the deeper reason is just “pick a unit” – 8 became the default largely through Material Design’s influence. This site runs a 4px-base ladder (4, 8, 12, 16, 24, 32, 48, 64, 96); the grouping lesson lets you overlay it on the page itself.