pub const BACKDROP_UNDERLAY_EPSILON: f32 = 0.005;Expand description
The backdrop quad’s stacking offset below its layer’s first stolen item.
stack_z_offsets::BACKGROUND_COLOR is 0.0, so an explicit negative
epsilon is required to sort strictly under the content composite quad
(which sits AT the first stolen key). Per-node z offsets span −0.1..0.08
and adjacent stack indices differ by 1.0, so 0.005 can never sink the
quad under a preceding sibling.