Top panel: Snapshots of density (Δ), collapsed fraction (f_coll), and neutral fraction field (x_HI), gradually in order from left to right, for the fiducial model utilized to generate the mock dataset as described in Section 4. Bottom panel: 21 cm power spectra (⟨δT _b⟩² Δ₂₁ ²), 21 cm and density cross-power spectra (|Δ_21 × δ ²|), and the bias of cross-spectra (b_21 × δ ²) for the corresponding model, gradually from left to right.