src/transparency-iframe.html is a tiny html+body=transparent
stub we serve at /transparency-iframe.html so dev hosts (and
future debug tools) can include it via iframe to confirm that
cross-origin iframe transparency is working in the target
browser without involving any of the Artstr embed JS.
Validated end-to-end:
- srcdoc iframe → magenta shows through ✓
- cross-origin minimal page → magenta shows through ✓
- cross-origin Artstr embed → magenta shows through the
Computer_Icon's transparent ring ✓
What looked like opaque white on the stress-test host was the
artwork's natural fill + the host's pink/yellow checker reading
as noise rather than see-through. Magenta on a flat backdrop
made the transparency unambiguous.
