It's important to sew the triangles on in the reverse method, as shown. Then trim evenly along the edge of the blue square chopping off triangle points.
Until then, keep stitchin' . . .
Back in the days when I typed ER reports, winter often produced a list of casualties. A small patch of ice on the porch or driveway and a newspaper waiting to be retrieved could be a lethal combination, especially for those over 70.
If you keep a small box of rock salt handy and sprinkle just a bit on your steps, porch, or driveway, you may save yourself a trip to the doctor. And if you have an elderly neighbor, why not buy one for them also. For under $2.00, it's an easy gift to give.
Until then, keep stitchin' . . .