Resolve #420

- Remove `margin-top` for the first child in various list items, to improve alignment.
- Add examples of lists to `docs/tests/styling`.

Cosmetic

Works for description lists with multiple `dt` and `dd` elements.

(cherry picked from commit 2b153ed074811e735aaa58d57a3fcdf7838e17f5)

Deduplicated anchor heading svg,
Anchor heading svg is now centered for heading

Thought the description list could benefit from some CSS Grid powers