Every number here is measured from the same layout-data.js the simulator
renders from, so this page cannot drift from what actually draws. Values are in screen
pixels on the 480 × 800 panel. Where a number sits off a round value it is flagged, so
the design intent and the slips are easy to tell apart.
Distance from each icon's centre to its declared grid axis. Everything is snapped, so the only residual is the half pixel an odd-width icon cannot avoid when its position is rounded to a whole pixel. Anything larger here means something has drifted away from the grid.