background 04（b952ba9b）

Use this MotionSites background video as a looping website background asset.
Title: Background 04
Category: background
License: 免费
Video URL: https://d8j0ntlcm91z4.cloudfront.net/user_38xzZboKViGWJOttwIXH07lWA1P/hf_20260419_065931_e3ca7b53-d32e-4ad5-81de-dc9d6fcfda6d.mp4
Local thumbnail: thumbnails/b952ba9b-f371-475c-9879-dc8613804aff.jpg
Implementation requirements:
- Render the video as a muted, autoplay, looped, playsInline background layer.
- Use object-fit: cover and keep the focal motion visible on desktop and mobile.
- Add a readable overlay only when foreground text needs contrast.
- Keep controls hidden for decorative background use, and provide a poster/thumbnail fallback.
- Respect the MotionSites authorization state before using this asset in a commercial project.