Styling Parent Page link in Widget

Hi there – hoping that you can help me to style the Parent Page link that appears in the widget using this plugin. There’s no CSS class added to the generated
ul that I can find – is there a line I can add to the plugin to have it assign a class to the Parent link?

This is for the WIDGET in my sidebar – here’s what I want to do:

Parent Page <– in bigger text than children below, via CSS class
Child <– in smaller text than parent above
Child of child
Child
Child

I don’t know much PHP, but if you tell me where to paste something that will give me this functionality, I can make that work. ?? Thank you!
https://www.ads-software.com/plugins/sb-child-list/