CSS editor lets users style :hover without selector

[lexoyo]

comes from this issue

Silex allows creating a raw :hover selector (without element, class or ID). This should not be possible.

Steps to reproduce

1. Select the body
2. Add hover as a class
3. Remove the ID from the selector
4. This results in a plain :hover rule
5. Applying styles here breaks the project (not showing up in the list of styles)

Demo video

Expected behavior

Silex should prevent creating a bare :hover selector

Actual behavior

A raw :hover selector is allowed and causes the whole project to vanish in mobile portrait mode