You're right, they didn't use to have rounded corners: https://web.archive.org/web/20131201025758/http://www.nngroup.com/ https://web.archive.org/web/2013120102

You're right, they didn't use to have rounded corners: https://web.archive.org/web/20131201025758/http://www.nngroup.com/ https://web.archive.org/web/20131201025758/http://www.nngrou... That was when border-radius already existed. Of course their older designs didn't have rounded corners because that would have required using images, which would have made the page load slowly: https://web.archive.org/web/19990222172600/http://www.nngroup.com/reports/ https://web.archive.org/web/19990222172600/http://www.nngrou...