Many front end designers do a good amount of front end development, and the reverse is also true. At least most that I've met. If design is most important, you

Many front end designers do a good amount of front end development, and the reverse is also true. At least most that I've met. If design is most important, you want a front end designer, and specify that CSS/JS experience is preferred. If development is the focus, ask for a developer who knows their way around Photoshop/Illustrator and ask for some design examples to see if they have the design chops you need. There are some out there who are amazing at both but they will cost ya.