Re: [css3-background] border-radius color transitions using gradients recommended but undefined from Zack Weinberg on 2010-01-29 (www-style@w3.org from January 2010)
How to Create Border Animation using CSS ? - GeeksforGeeks
CSS Border transitions
45 CSS Border Animations
45 CSS Border Animations
How to use CSS ::before and ::after to create custom animations and transitions - LogRocket Blog