- 1:1 start-aligns. The centred flex item overflowed both sides and the
start was unreachable; measured, a 3000px picture hid its leftmost
980px. Auto margins still centre a small picture.
- Drag lifecycle: a move with no button ends the drag, so a press
released outside the stage never pans on a later hover. Capture is now
load-bearing in a test. The threshold is 4px of total movement.
- A press on the stage's own scrollbar is never a pan. The arrows clamp
to the stage's client box, so they are never under a classic
scrollbar. The test runs a browser without --hide-scrollbars and
asserts the gutter exists.
- Stacked, the arrows' CSS spot is the stage's centre (30vh), set in
view.html because base.html lost to the page's later rule.
- The stage reveal is `hidden` until bound, and keeps Fit's drop shadow
when revealed. A blurred picture composes blur() drop-shadow().
- The mode follows another tab. A failed or unknown size returns the
arrows to their CSS spot.
- Tests: object-position, vertical centring, the Fit half of
aria-pressed, a storage read that throws, a large picture's toggle,
Fit forgetting 1:1, single-axis pan.
- Declared: the r2b reveal test reads "no blur" (the shadow stays), and
the r2_flow 360px-offset row is retired.
Mutation tables 137/137 across four. 810 passed.