logicalWidth/viewportHeight can go non-positive for a narrow container
on a heavily zoomed-out board, where outerCardInset (which grows as
canvasScale shrinks) can exceed the container's own un-inset size.
That non-positive scale then feeds into a division (Infinity/NaN into
--board-canvas-ui-scale) and is used as zoom directly (invalid or
collapsed content) - flooring it well above zero avoids both.
Bergasha
c82965067c