The heart is the signature. Every BBS artifact ends with a jadeite heart linking home — that's the whole rule. Lockups are composed from the parts — two wordmarks and one heart — never saved as flattened artwork, so the heart is current everywhere by construction.
The only place the heart legally stops being jadeite: a medium that physically cannot produce it — one-ink screen print, engraving, fax, laser etch. Not for screens. On screen you always have jadeite available, so an unreadable ground is fixed with a scrim, a keyline, or a plate — see when you can't control the ground.
Clear space is one heart-height on every side. Nothing — type, edges, other marks — enters the inner box.
Below these widths the heart closes up and the wordmark stops being legible. Each specimen below is drawn at its true minimum. Total width is a fixed multiple of the cap height — 8.427× horizontal, 4.927× stacked — so divide the width you need by that to get --bbs-lockup-size.
At icon sizes the heart stands alone — never the wordmark. Centred, with the heart at roughly 55% of the tile.
<a href="https://builtbystephen.me">.The lockup is fixed artwork. Scale it, and nothing else.
Scrim the image, then keep the heart jadeite. A scrimmed photo puts jadeite around 6.8:1 — well past the 3:1 WCAG asks of a meaningful graphic — so there's no reason to drop the thread. Fix the ground, not the mark. Drop your own photos in to test. Full working at mono heart on screen.
User-uploaded backgrounds, partner templates, print-on-demand. You can't guarantee a ratio you don't own, so give the heart its own ground instead of recolouring it.
The plate is the only route that keeps the heart jadeite and guarantees the ratio — you own both sides of the contrast. Prefer it. It's solid on purpose: at 84% over a pale photo jadeite drops to 2.2:1, under the bar, so the plate is the one surface in the system that is never glass.