Median absorption lines (thin lines) detected from our 238 foreground–background galaxy pairs, including all foreground galaxies (red) and background galaxies split by their projected angular separations: < 118 (blue), 118–165 (green), 165–20″ (cyan), and 20″–23″ (magenta). The bold lines indicate the Gaussian profile fit to measure the strength of the line absorptions (see Sect. 4.1).