Hiding a column

[futpib]

Something like the following could mean "hidden on xs, full width on sm".

{
  span: {
    xs: 0,
    sm: 1
  }
}

[futpib]

Or maybe this would be a better choice:

{
  hidden: {
    xs: true
  }
}

[fredbutters]

Bootstrap 4 uses styles like hidden-sm-up and hidden-lg-down. Maybe just adding support for those attributes would be enough.