The boxes change their width property.
calc(100px)
calc(100px + 30% - (2rem * 3 + 20px))
calc(100px + 30% - (120px / (2*4 + 3 )))
calc(50% + 60px)
calc(50% - 60px)
calc(50% + -60px)
calc(50% + 50px - 10px)
calc(50% + 3*20px)
calc(50% + 3 * 20px)
calc(50% + 10.5pt)
calc(50% + .5pt)