Function sync_radio_visuals 

pub fn sync_radio_visuals(
    parents_q: Query<'_, '_, (Has<Selected>, &RadioStyle), With<RadioButton>>,
    dots: Query<'_, '_, (&ChildOf, &mut Visuals, &mut StyleOverrides), With<RadioDot>>,
)

Keep every .radio-dot child in step with its parent’s Selected marker: selected_bg while selected, the dot’s own fill otherwise.