For the first time I'm in the position where I'm helping interview potential front-end developers. (The other interviewer is more business & PM-focused, although he is a former developer.) I probe for knowledge and background in css, js, and other related technologies, but those questions are really just testing for lingo. I feel that it'd be unfair to ask very specific questions about css when we're not infront of a computer, because my style of programming css is a lot of guesswork.

I've also been given websites that these web developers have written-- is that enough to go on for interviewing front-ends? We're also looking for general aptitude, rather than a databank of knowledge.