Edit put a fixed 420px band above a scrolling column, so the preview was a letterbox in the mode where
changes are actually being made — and there was empty panel below the controls while the thing being
judged was squeezed.
One column now, for both modes, and it never scrolls as a whole. The preview is flex-1, so it is always
as tall as whatever is left. The controls are shrink-0, so they are exactly as tall as their content
and no taller. Edit takes height from the preview and only as much as it needs.
Capped at 55% with their own scroll, because shrink-0 alone would let a short window hand the controls
everything and leave the preview at nothing — the same failure in the other direction.
The frame is also capped at the device's real height. A 390x844 phone in a 1200px panel would otherwise
be drawn as a phone 1200 pixels tall, which is not a phone. Past that it stops growing and the space
stays empty, which is honest: there is no device that shape.
Two modes were two return paths; now switching modes hides a block rather than rendering a different
component.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>