[Python] Correct selector to target a 'Textual' SelectionList selected items' text?

I have a Textual SelectionList in my Python console app:

...
yield SelectionList[str](
*tuple(self.selection_items),
id="mylist")
...


In my associated .tcss (Textual CSS) how would I target the text of a selected item? I'd like all selected items to have a different text colour.

Interpreting the source of SelectionList, OptionList and ToggleButton I've tried a variety of selectors targeting the -on variant of the ToggleButton child of the SelectionList component (globally and via an #mylist id selector, and while I can change the colour for all items I'm unable to restrict it to just the selected ones.

Continue reading...