After being installed at the bottom. Pull up the zipper and determine the position of the other zipper, which must be aligned with the seam edge. You can repeatedly pull up and down the zipper to adjust the position, and look back and forth, which is why it is recommended that novices sew 0.7cm first and then sew it next to the zipper teeth. The finished product is as follows, with no invisible zipper marks on the front.