https://css-tricks.com/the-mistakes-of-css/ — This article talks about some mistakes in CSS. For example, z-index doesn't work on all elements, and background-repeat should default to no-repeat. People question if CSS Flexbox and CSS Grid should share more syntax. Fixing these issues isn't easy because websites were built with these quirks. Changing them would break sites. The CSS Working Group deserves praise for designing new features that can't be changed once shipped.
Chris Coyier