Mara: remove the 90em max-width so the dashboard fills wide
screens instead of boxing content into a centred column with
empty margins. `padding: 0 1.5em 1.5em` stays as the small
edge-of-viewport gutter; `.dashboard-chrome { margin: 0 -1.5em
... }` continues to pull the sticky chrome bar edge-to-edge
through that gutter.
c015f62764