Ask HN: What would JavaScript and CSS look like if it were created today?

JavaScript and CSS have evolved since their creation, and are currently used to create software that we never would’ve imagined possible judging from their humble beginnings.

That said, both technologies have some warts, largely due to design mistakes and backwards compatibility issues.

What would JavaScript and CSS look like if they were created today?

In other words, what design decisions were mistakes? What design decisions were good? What would you keep, what would you toss?