Invalid scoping for :root selector

[yhatt]

Marpit v2.3.0 has invalid scoping for updated :root selector.

/* @theme theme */
:root {
  background: yellow
}

/* Bad */
div.marpit > section :where(section):not([\20 root]) {
  background: yellow;
}

/* Good */
div.marpit > :where(section):not([\20 root]) {
  background: yellow;
}