The separator renders data-md-menu-separator and takes its 1px line,
8px block margin and 16px inset from menu-separator.css in
material.components (plan step 36, actions).
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9
