border-beam

A bright comet that travels an element's border. Part of motion-anything; obeys MOTION-SPEC.md. Technique popularized by Magic UI, reimplemented dependency-free (pure CSS).

When to use it

• A single "new" / "featured" card or a hero CTA that should feel lively for a beat.

When NOT to use it (restraint)

• Several at once (competing beams = noise). One per view.
• Calm/serious contexts — or when a quieter full-border glow fits: use shine-border instead.