Constant LIGHT_SHADOW_SCALE 

pub const LIGHT_SHADOW_SCALE: f32 = 0.45; // 0.449999988f32

How much of the dark material’s shadow a light material keeps.

A drop shadow is black in either polarity, so equal alpha does not buy equal weight: the same wash that a dark ground swallows whole lands hard on a pale one. At 45 % the light shadow reads as the same lift.