* web_editor

- Restore the preservation of Odoo text-muted color (the rule became
  !important with BS4 and had thus to become !important in the
  preservation mixin).
- Preserve base design in the "new content" menu (which now uses
  text-muted). Indeed, in some themes, the "new content" links were not
  even visible anymore.

closes odoo/odoo#28666