Auto margin classes

[mdt2]

Could be nice to have classes for auto margins:

.util-margin-left-auto {
  margin-left: auto;
}

[zastrow]

This can be done already. Add the key/value to the spacer map.

[zastrow]

On second thought…it might make sense to set this as a default.

[zastrow]

What needs to be done here is add auto to the default spacing system map: https://github.com/sparkbox/sparkle/blob/main/globals/spacing/_map.scss