Great guide. Interested to see the advice on doubling type-size for contrast. I thought sticking to the typography scale (10, 11, 12, 14, 16 etc) was a golden

Great guide. Interested to see the advice on doubling type-size for contrast. I thought sticking to the typography scale (10, 11, 12, 14, 16 etc) was a golden rule. The x2 factor looks good though. And now I can reliably type -, –, and –. That alone's worth the read.