Switch more info callouts from auto to 100%

I can't remember why we were using auto (pretty sure there was a reason),
but it's broken now. Switching to 100% fixes the issue.
Style tweaks to module_banners for small screens

Removing the float: none; on small sections may make small screen
modules break, but we don't have any of those yet.
Merge pull request #70 from alphagov/restricted-labelling-tweaks

Restricted labelling tweaks