CSS Borders: The Basics And Rounded Corners - Vanseo Design
Code a Simple Folded Corner Effect With CSS | Design Shack
css - How can I show only corner borders? - Stack Overflow
Re: Idea : replacement for border-radius, a more complete corner styling property. from Andrew Fedoniouk on 2011-09-01 (www-style@w3.org from September 2011)
border-corner-shape is in danger, and you can help! • Lea Verou