How Far the Box Can Drift

A ground-truth box around a parked car is $120$ pixels wide and $80$ pixels tall.

A detector returns a box of exactly the same size, $120 \times 80$, at exactly the same vertical position — but shifted $d$ pixels to the right. The two rectangles therefore share a vertical band that narrows as $d$ grows.

This benchmark is strict: a detection counts as correct only when

$\mathrm{IoU} \;=\; \frac{\text{area of the intersection}}{\text{area of the union}} \;\ge\; 0.75$

What is the largest whole number of pixels $d$ can be while the detection still counts as correct?

Answer with a whole number of pixels.