You can absolutely develop your skill as a designer. If you can look at a site and say to yourself "Now that’s a great design", and then look at something you’ve designed and say "This isn’t nearly as good", then you have what it takes to improve. It’s true that CSS/HTML coding is more of a "left-brained" bookwork type skill and design is more of a "right-brained" artistic skill, but both can be trained and developed with practice.
Just designing, designing, and more designing is the key. If you design 10 websites in 3 months, the 10th design is going to be much stronger than your 1st. In fact, you’ll probably be disgusted by your 1st design :oops: You can also go to school for design. I’m sure people’s opinion on this greatly varies, but I feel I learned quite a bit from my random-state-school art education. After all, going to design school is basically an exercise in repetition. Guess what you do in drawing class? Draw and draw and draw and draw and eventually you get better at it. In-born talent certainly doesn’t hurt, but anybody can become a good designer.