CSS has many weird is corner cases where you have an issue and after a lot of debugging, trying things, getting mad you find on Stack Overflow that you add a ilogical rule like "min-width:0", so css is ok until you end up in a tricky problem where you need to understand how the css code works under the hood to fix. Other issue with css is too big and complicated, good layout modes are added but we stil ahve the old ones and you need to understand everything because most developers work on existing code and you hit all kind of layouts like floating,absolute,relative. Flexbox layout seems better but stil worse then layouts I have seen in MXML and WPF. So ignoring JS that you could replace, getting a new GUI for the Web inspired by MXML/WPF or QML with a sane subset of css would improve the situation.