Hint, ActionRow, Toolbar, EmptyState and ExternalLink replace the muted
text, button row, refresh bar, empty line and _blank anchor that each page
restyled under its own class. ExpandableCard (with a loading twin) holds the
builds and recent-runs cards, which had identical head and body CSS. The
create form's raw checkbox becomes CheckboxField. The components page shows
each new piece.
The alerts and issues tabs are one reports tab in the nav. Each page, unchanged
inside, is a card that starts shut and reads nothing until opened; the alerts
header's link, button and refresh picker move into the card's body. /alerts and
/issues redirect to /reports. Docs follow.
