Did November's revenue cost us the margin?

bars: revenue (left) · line: margin % (right) · illustrative
R0R5m R10m 10%18% 26% MayJul SepNovDec 14% — margin floor Record bar, lowest line: November's promo bought revenue at 14% margin, and December only recovered to 18. Both axes zero-anchored and labelled — dual axes lie easily otherwise.