Height test — top marker

loads late, block must grow
second late image

Bottom marker. If you can read this without a scrollbar inside the block, height tracking works.

Escape test

FIXED OVERLAY — must stay inside the block, never cover the admin UI.
top-navigation link

Embed test

Green box, red background — inside the block only.

This line USES the hijacked classes, so in here it should look broken: huge pink text on black, round, red glow. That proves the CSS is alive — just caged.