Background

The Grid mixins must cater to Vector needs in order to be useful. We also need to settle on a public mixin API, that's not going to change quickly after again to prevent going through work- and time-intense deprecation process

Goal

Ensure evaluation of new Grid mixins as possible replacement for Vector's CSS Grid, see T303484.

Acceptance criteria for done

• Review Codex Grid mixin approach and documentation
• Evaluate if code approach would fit as 1:1 replacement (no real code replacement work needed for now)
• Possibly share and define boundaries of Codex Grid vs skin additions (thinking Grid template areas for example)