Function insets 

pub fn insets(
    top: f32,
    right: f32,
    bottom: f32,
    left: f32,
) -> Rect<LengthPercentage>

Padding per side in CSS order (top, right, bottom, left). Negative values are clamped to zero: taffy treats a negative inset as undefined and a caller subtracting an overlap can otherwise drift below it.