Surfaces

The surface system is closed — five named surfaces, no improvisation.

• Glass — one recipe, three densities (soft / default / strong).
• Blooms — peach / lavender / sage / amber backdrops.
• Sheet — overlay primitive with --sheet-scrim-tint and --sheet-card-tint.
• Code — light glass, not dark slate.
• Glass rule — when glass is allowed and when it isn't.
• Dark — [data-theme="dark"] rebind.