Easy things are easy in CSS. Hard things are... possible. Sometimes barely so. Sometimes impossible without JS. BUT, the easy things are generally easy.
In job interviews, I've been handed code in various languages from assembly to C to Java and asked to figure out what that code does. It can be an interesting challenge, and while I'm certainly not the fastest to figure it out, I usually can.
Give me a bunch of CSS and ask me what it will do... even with the docs in front of me, I am almost certain to get much of it wrong. And I suspect even experienced front end devs (I've never done front end professionally) would struggle with such a challenge.
