Heatmap outlines are inconsistent: hover and focus draw inset, column highlight draws outward

[realmarcin]

Found reviewing #49.

Four rules now outline a heatmap cell and they do not agree on where the ring sits.

• td button:hover gained outline-offset: -2px, so hover draws inside the cell.
• td button:focus-visible draws two inset bands.
• td.hi draws a 2px outline with no offset, so it sits outside the cell.
• td.sel does the same.

With border-spacing cut from 3px to 2px, the outward outlines of two adjacent highlighted cells each claim the full 2px gap between them, so the column highlight reads as one continuous band instead of nine rings. For a whole-column highlight that may be the better look, which is why this is filed rather than fixed. Worth a decision either way, so the four rules stop disagreeing by accident.

Separately, td.sel is dead. The class is declared in the stylesheet and never applied: state.sel in the graph code is unrelated and no code path adds sel to a heatmap cell. Searched the fragment source and the generated page.

🤖 Generated with Claude Code

https://claude.ai/code/session_01BXHrBTSU8fU4Zg7HfaMKs9

[realmarcin]

Correction: td.sel is not dead. _fleet/fleet_fragment.html:736 applies it to the clicked cell inside the cell-panel click handler. I searched for classList near the class name and missed that line because it toggles on td while testing td.contains(b).

The rest of the finding stands: hover and focus draw inset, td.hi and td.sel draw outward, and at 2px border-spacing two adjacent outward outlines meet. td.sel marks a single cell so it never abuts another selected cell, but it is still the odd one out against the inset hover ring on the very same cell.