I think it has a lot more to do with memorization of all the little quirks on what works on what browser and what doesn't.
With languages like C#/Ruby/PHP/JavaScript, I find that I can soak up that knowledge better than HTML/CSS, because I find it consistent and organized (...not too sure about PHP's quirky API naming conventions). For CSS, it just seems like there is a myriad of tricks you gain through out the years, and I guess it just takes more effort to get good at it.
Exactly. Programming is logical. Styling isn't. Knowing that `margin: 0 auto;` centers elements in CSS isn't a left-brain, right-brain thing. It's just something unintuitive that you accept until you stumble upon the New Way of doing it.
With languages like C#/Ruby/PHP/JavaScript, I find that I can soak up that knowledge better than HTML/CSS, because I find it consistent and organized (...not too sure about PHP's quirky API naming conventions). For CSS, it just seems like there is a myriad of tricks you gain through out the years, and I guess it just takes more effort to get good at it.