forsterkning med vliseline: https://www.yarnspirations.com/blogs/how-to/mic-20170328-grand-openings-in-seam-buttonhole?srsltid=AfmBOopt7PHNtOWV27mJ-vj9FxW65MhpAzyVjg3SSc56VsSVFC6LHos8
veiledning https://www.threadsmagazine.com/2021/08/23/sew-a-button-placket-extension-with-in-seam-buttonholes