Rectangles with rounded corners are mathematically wrong. Once you know why, you can’t unsee it. Squircles, made iconic by Apple, are finally supported in browsers by the new CSS corner-shape: squircle property. I will show you how to approximate one squircle corner with just three pixel-perfect Bézier curves, so you can use squircles everywhere: canvas, SVG, clip-path, and even game engines. Your eyes deserve curves that actually make sense.
I prefer round[ed].
I don’t find them pleasant. I find them irritating.
Rounded square makes use of the space it reserves/square-fills. Squircles seem wasteful and confusing. They do not represent any common physical shapes, and waste/discard space they could use. They look like an old CRT.