How did the double helix structure match Chargaff's observations?

Chargaff observed that the number of Guanine units in a section/piece of DNA was the same as the number of Cysteine units and that the number of Thymine units equaled the number of Adenine units.

This matched the double helix structure because Cysteine pairs with Guanine, and Thymine pairs with Adenine - meaning that Chargaff was right in that there must be an equal number of Cysteines and Guanines as well as equal Thymines and Adenines.