I like this approach more because I can scan the code that renders the Box component and easily spot that it takes two children. If the Box took any props, they'd be within the opening <Box> tag, and they would be distinct from any children props.

The link name is not very helpful, it doesn’t explain what it does very well.

One last bonus: CSS variables can be written in a way that makes it easier for human programmers to understand. If you just see hex code #93e9be, you won’t know what color it produces, while --brand-green makes clear the purpose of the variable.