The problem with CSS is that it’s not very intuitive and too flexible. You need to know how display and position works to understand the basic centering a div example. If you forget to change the display to flex you don’t get an error, it’s still valid CSS. You can examine the element in the browser but you’ll need to know to look for the issue there.

Then you’ll need to inline and block elements, etc.

And it’s a pretty unique system in general.