Function logical_border_widths 

pub fn logical_border_widths(
    top: f32,
    right: f32,
    bottom: f32,
    left: f32,
    start: Option<f32>,
    end: Option<f32>,
) -> BorderWidths

Per-side border widths where start/end, when given, land on left or right according to the writing direction.

A logical side overrides the physical one it lands on: an author who wrote both named this edge twice, and the name that describes its role is the one that was talking about the current layout.