Move font-size delaration to html element

[robwierzbowski]

Since rems are based on the font-size of the html element we should probably move the font-size declaration there. This would set up reasonable expectations for the developer (edit font-size, change rems) without changing any current behavior (body { font-size: 1em } is implied).

The original commit to add body { font-size: 1em } is here. It seems it was added as a developer convenience, while line-height needed normalization.

[necolas]

May as well just change the selector from body to html. I usually set all these styles on the html element.

[robwierzbowski]

It would be ideal to move line-height to html too, to keep related declarations together. Not sure / haven't tested if that causes issues in less capable browsers though.

[robwierzbowski]

Looks like we cross-posted. I'm all for it, PR revised.

[necolas]

Thanks. Applied in ab6b2fc