Change onsizechange handler to use min-width instead of width,
treating the app's reported size as a floor rather than exact.
Use min(Xpx, 100%) to allow shrinking with container.
Also remove outmost max-width constraint and simplify iframe CSS to
allow apps to demonstrate responsive growing.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>