Power spectrum relative to tCOLA (top panel) and cross-correlation with respect to tCOLA (bottom panel) of redshift-zero sCOLA density fields, in a 200 Mpc h⁻¹ box containing 512³ dark matter particles. Different sizes for the tiles (represented by different line styles) and buffer regions (represented by different colours) are used, as indicated in the legend. The vertical lines show the respective fundamental mode of different tiles, the light grey bands correspond to 3% accuracy, and the dark grey bands to 1% accuracy.