A — red = top:56px, blue = top:3.5rem (must be the same line)
B1 — section header with top:56px
B2 — the same with top:3.5rem, as the site writes it
C — widths: 16px, 1rem, then 56px (red) vs 3.5rem
Rows 1&2 must match, rows 3&4 must match.
D — the same x10: 160px vs 10rem, 560px vs 35rem
Red is px, green is rem. Divide any overhang by 10 (resp. 35) to get the
error in one rem.