By default, CiviCRM on Drupal's "Bartik" theme and Backdrop's "Basis" and "Seven" themes cause CiviCRM inline fields to display with horizontal scroll bars, which hurts usability (see screenshot 1).
In Drupal, the civi_bartik theme fixes this (see screenshot 2). Is there an equivalent theme for Backdrop CMS?
civi_bartik
just force the wrapper/container to be wider or is it doing something else? I just did a quick test in Seven and changing.container
to have a max-width of 1250px appears to be enough (if your screen is big enough). This doesn't help on smaller screens of course.