StoutFiles - 8:00 pm on Nov 27, 2012 (gmt 0)
I was in an interview recently for a migration role and I said that if I ever do get stuck on code I search it to find out the answer and the interviewer asked if I used w3schools, because their code is terrible.
People who take a course at w3schools and then proclaim they now know HTML/CSS are usually fooling themselves. Most people dash through it in a day, only using the built-in Try-It-Yourself! While you can learn from w3, and it's a decent place to go for refreshers, it's never something you'd want to put on a resume or mention in an interview, as it makes you come off as a novice.
I am definitely not saying you aren't proficient in HTML/CSS, but I can see how an interviewer might think that, and might not want to gamble on you with other applications on their desk.