Create general semantic size designations.

Following and GUISE-18, we need general semantic size and max-size designation classes. Here they are with the default values:

• (max-)size-marginal: 11%

• (max-)size-subordinate: 22%

• (max-)size-significant: 33%

• (max-)size-partial: 50%

• (max-)size-substantial: 66%

• (max-)size-full: 100%

These can be overridden using CSS variable, already implemented in GUISE-18: