A container's outer grid cell and its own inner content grid are sized by
two independent calculations that only agree when the container is
scrollable and expanded. When collapsed, or when non-scrollable content
needs more rows than declared, the inner grid keeps rendering at its old/
content-driven size while the outer cell shrinks or stays fixed, leaving
an invisible-but-space-occupying box that inflates the board's scroll
height into a visible empty gap below the container.
Pass the outer instance's collapsed row count down as a
viewportRowCountOverride so the inner grid matches it exactly when
collapsed, and grow the outer placement's height to the already-computed
content minimum (getContainerMinimumSizes) for non-scrollable containers
so it stays in sync with the inner grid's own growth.
A container's own visible card is inset from its allocated board cell
by the board's standard per-item gap, but items inside it are
positioned in a coordinate space sized to the un-inset column/row
count - so without correcting for that, items (not just the grid's
own box) spilled past the container's right/bottom edge by that
inset amount, worse the busier/more zoomed-out the board is.
Scales the container's inner grid content down to fit the actual card
size, using the same zoom mechanism the board's own top-level canvas
uses for its whole-board zoom, just one level deeper. Corrects
--board-canvas-ui-scale to compensate so icon/text/custom-CSS sizing
inside the container isn't affected - computed as a plain JS number
rather than a CSS calc() referencing the property's own inherited
value, since custom properties don't have a sequential/temporal order
within the same element and doing so is a circular reference that
silently invalidates the whole property for every descendant.
Also fixes the collapsible container's label bar poking above the
card's rounded top border via a negative offset - it now sits flush
inside it.
Thomas
Bergasha
ajnart