DO
Use Squeak only for hero and display headings — never body copy or sub-headings
Use #F54E00 as the single primary CTA per view — PostHog's brand orange-red
Apply radius-lg (20px) to cards, panels, and modals — PostHog's signature shape
Use tan (#EEEFE9) card backgrounds on the warm off-white (#F5F5F0) page in light mode — the depth is intentional
Use IBM Plex Mono for event names, user IDs, and all identifiers in data tables
DON'T
Use #F54E00 for error states — use salmon (#F35454) or pink (#E34C6F) instead
Use pure black or cool gray for dark backgrounds — dark bg is #131316, a near-black with warm undertone
Apply radius-lg to small buttons or inputs — those use radius-sm (4px)
Mix Squeak and IBM Plex Sans at the same heading level — Squeak is display-only
Swap tan cards for white cards in light mode — white on white collapses surface hierarchy