Ask HN: If you were to reinvent the web, how would your HTML/CSS/JS look like?

A recent discussion on HN [1] has showed that surprisingly many people do not like HTML/CSS/JS. If you were to reinvent the web, how would your version of client-side look like? How would you simplify/improve markup language and style sheets? Would you replace them by a single language?

[1]: https://news.ycombinator.com/item?id=12477190