Looks like a bad themes/bootstrap_darkroom CSS and the form field label being displayed inside the field, along with the placeholder that vanishes when typing. It is moved to outside the field if the bmd-label-static class is removed from the label element. Don't ask me where|what to change in the bootstrap_darkroom theme..

Thank you very much! How can I change this so that it remains after an update of the theme?

I have now anchored it as custom-css in the theme settings, but have also written an issue for it in Github. The code that works for me now is this:

.bmd-form-group {
padding-top: 2em;
}

Thanks again for the quick help.