Plan step 23, containment.md § Missing ("Lists: leading video slot").
`<x-list-item video="…">` (or `<x-slot:video>`) draws M3's leading media
in its landscape sizes: 100×56px in a two-line item, 114×64px in a
three-line one (ListTokens' LeadingVideoSmall 56×100dp and
LeadingVideoLarge 64×114dp), with the small corner the leading image
takes. The tallest element sets an item's height, so a video lifts the
item to at least the 72px two-line row — 56 + 2×8 is 72 exactly, and
64 + 2×12 is 88.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9
