Visual break between widgets

I think the answer to this is probably “change the css and use javascript to …” but I’m hoping I’ve overlooked a simpler way. What’s the best/simplest way to add some kind of visual break between widgets? They all kind of blur together, which maybe only I notice because I’m debugging and have eye strain from reloading the apps pages. A simple

between them would suffice, really, but I don’t see an obvious way to get that into the page via the form.yml.erb file.

You can add css classes to form widgets.

With this definition (mb-5 being margin for bottom 5 bootstrap class)

    widget: number_field
    class: 'mb-5'

gives me this, with all the space below it.