See demo page here:
The slider doesn't have a width set but it's in a fieldcontain. This makes it very narrow compared to the same thing, just w/o the fieldcontain wrapper:
Fixes #3586 — Scopes set fieldcontain width (25%) in header/footer to…
…olbars to fieldcontains with ui-fieldcontain-left/right classes (the addition of which is still in progress).