Both rows inside the mobile stack were capped at the page's content width. Below
768px that cap does nothing, and from lg up the stack is hidden, so the gap it
left only showed in the band between: the ground and its two rules spanned the
screen while the tab cells, the dividers between them and the bar's own rule
stopped 66px short of each edge at 900px. The active tab's fill ended in mid air,
which is the tell.
A bar pinned to the bottom of the screen reaches the sides of it, so the tab row
loses the cap outright. The bar keeps it, but on an inner wrapper: its text is
still page copy and still lines up with the column above it, while the rule that
divides it from the tabs now runs the full width like the two the stack already
had. The cap could not simply move to a parent, because the element carrying it
is also the one .mo-out slides out at the closing bell, and a rule left behind
by a departing bar is a worse artefact than the one being fixed.
Heights are untouched, so the hand-kept TAB_ROW and BALLOT_BAR reservations
still land on the nose: 119.5px of stack against 119.5px of padding.
Co-Authored-By: Claude Opus 5 noreply@anthropic.com