Here is a cool tool to come out of Macromedia Consulting. It's a Flex CSS explorer. You can interactively control the look of all of Flex’s built in components and it will generate the appropriate CSS code. It doesn’t see to work correctly with some custom colors, but it works well enough that you can use it to see what the CSS property is to produce a particular result. Although the application doesn’t like some colors, Flex itself seems to compile them just fine.