Replace line-height with ratios

[ArmorDarks]

This one is tricky.

We might allow to specify ration instead of px value for base line-heights:

Instead of

$ekzo-line-height-ratios: (
  base: ekzo-font-size(base) * 1.5,
  blog: ekzo-font-size(text, blog) * 1.5,
) !default;

Do

$ekzo-line-height-ratios: (
  base: 1.5,
  blog: 1.5,
) !default;

The issue here is that it seems to be more limiting... Need to think about it better.

[ArmorDarks]

So far it seems to be undesired at least for base line-heights, since it will affect font-sizes, set with % — they will break out of grid with line-height set in ratio.