A successful HTML response is only the beginning of a website request. The browser still needs stylesheets, scripts, fonts and images. If those assets are missing, a page can look healthy in a basic uptime check while users see a broken experience.
Check the dependency chain
Verify the document response, then request representative assets from the same hostname. Check status codes, content types, certificate validation and cache headers. A 200 for HTML does not prove that the files referenced by that HTML are available.
Test what users actually download
Choose one CSS file, one JavaScript bundle, one font and one image. Test them from the public domain over HTTPS, following redirects. Record the result from the live edge, not only from the origin. This catches host, path, certificate and CDN mistakes that a homepage-only check misses.
Make the check repeatable
Keep a small list of critical assets and run it after deployments, DNS changes and backend cutovers. Alert on unexpected status codes, content types or certificate problems. The goal is simple: prove that the whole page—not just its first response—arrives intact.