Ah, Yes, the 3x3. Whenever this pops up, I remember a lot of fond memories of the early days of front-end development. I wrote about ours at https://brajeshwar.com/2005/splice9-bitmap-window-resizer-co...

I remember “feathering” the curves in Photoshop for a smoother finish to the rounded corners. My team, especially the new ones, would go -- heck, the trick, the trick, we learn a trick. ;-)

The struggles were real, and the fun was short and intermittent but worth every moment.