Shadow root inside a shadow root

Expected: three nested labelled frames — outer (blue), middle (green), inner (orange) — each drawn by its own shadow tree. Each level parses its own declarative template out of the level above it.

Slots chained through two levels

Expected: "document content" appears inside both frames — the outer component forwards its slotted light DOM into the inner component's slot, so the text travels down two shadow boundaries in one flattened tree.

Each level is styled independently

Expected: no colour bleeds between the levels above — the identical .lbl rule in each tree only ever paints its own label.