Remove `rem` font-size in `gl-link`

Description

Currently gl-link comes with it's own font size, which makes using in different contexts (like a header) difficult because we need to specify font-size: inherit; (see this comment for context).

This specific font-size must come from including gl-font-base... Is there anything that's dependent on gl-link having it's own font-size set? If not, let's either remove this rule here or add it's own font-size: inherit. 😄