Function floating_shadow 

pub fn floating_shadow(
    scene: &mut Scene,
    transform: Affine,
    rect: Rect,
    radius: f64,
    alpha: f32,
    theme: &Theme,
)

The two-layer shadow of a floating surface: the tight contact layer that defines its edge, under the wide layer that reads as distance (crate::tokens::Elevation::contact, crate::tokens::Elevation::floating), both along the surface’s own rounded outline. alpha scales both, for a surface still arriving.