Slug field layout broken when permalink is too long

[timobrembeck]

Describe the Bug

When the permalink of the parent page is too long, the slug field cannot be edited in the page form.

Steps to Reproduce

1. Create page with very long slug
2. Create child-page of this page
3. Try to edit slug of child page

Expected Behavior

The slug field should be scrollable horizontally

Actual Behavior

The slug field is fixed and the slug cannot be edited because it is hidden beneath the other elements

Additional Information