UA Ledger · Playable Test Bench · draft for review
Teaching laboratory. Cases run in this page against the authored functions. This is not a device panel, network approval, analytics-delivery proof or campaign result. Inputs are synthetic.
An end card may look centred while its button overlaps a reserved screen area. This fixture makes the bottom inset part of the layout calculation instead of decorative padding added afterwards.
Primary documentation: MDN: safe area (body read 2026-09-19).
| Case | Input | Expected | Fixed | Broken |
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The expected value is the button's top coordinate, not a visual approval. A correct top value cannot prevent a parent container from clipping the button or a host overlay from covering it. The useful invariant is that the declared button rectangle stays above the declared reserved area.