Bump @webref/css from 8.0.1 to 8.1.0

Bumps [@webref/css](https://github.com/w3c/webref) from 8.0.1 to 8.1.0.
- [Commits](https://github.com/w3c/webref/compare/@webref/[email protected]...@webref/[email protected])

---
updated-dependencies:
- dependency-name: "@webref/css"
  dependency-version: 8.1.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]