When a MonthGrid / YearGrid is rendered inside a DatePicker.Content
popover (via DatePicker.MonthView / YearView), the grid was using
inline-size:max-content while the picker-shell Footer below it stretched
to the popover's full content width — leaving an empty band to the right
of each row of cells.
Scope the override to `[data-popover-content]` so the standalone grids
on their own demos keep their natural max-content sizing. Inside the
popover, the grid root and the inner [data-*-grid] both stretch to 100%
so the 3 columns (minmax(0, 1fr)) distribute across the same inline
size as the footer.
Also added box-sizing: border-box to both grid roots so the padding +
border don't push them past the popover content area.
Verified at /uix/components/date-picker with kind='year' size='md':
popover content width = 288px, year-grid width = 262px (= footer width),
inner grid = 228px (= grid container minus padding). 3 columns align
flush to the footer row above.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
dev