The hard case. Four check circles per row, labels up to three lines. Steam's 22 px boxes at a 60 px pitch become 40 px circles in 80 px cells (hit 80 × 80); the column headers widen with them and stay sticky.
Focus in a multi-control row. The row only warms (white .06); the focused circle carries the focus: on a blue (on) circle a soft glow around it, on an empty one Steam's FocusRing as a light plate 12 px larger than the circle. Left / Right move between columns (Steam's own nav).
Disabled cells (the Feed column) stay at 40 % and keep Steam's saturate(.35). Empty cells are Steam's: no checkbox exists there.