1. Borders on ::before and ::after

This is the classic approach with three transparent and one colored border. It has the disadvantage that the clickable zone of a link is still a rectangle. Go for instance to the top left corner of the second link. You will notice that you are actually already on the third link.

2. Skewing and rotating ::after

With this approach the clickable zone is identical to the visual representation of a link - you move outside of the triangle and are on the next link.

3. Cutting off with clip-path: polygon()

A third way to achieve this is to use clip-path: polygon() . Browser support meanwhile is OK-ish .