Ignore margin overlap for this demo! Relative fonts based on your browser preference setting - typically 16px, so 16px = 100%.

H1: My font size is 2em and I have a margin of 1em

H1: My font size is 2em and I have a margin of 3em

H2: My font size is 1em and I have a margin of 1em

H3: My font size is 16px and I have a margin of 16px

My font size is 2em and I have a margin of 1em, but my parent font-size is set at 2em.

My font-size is 1rem and I have no margins

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