Tiny "Color Code" problem

I'm a student and recently I'm making a website in order to share the course with others And I got a pr开发者_高级运维oblem:

I'm trying to express the "Course Heat Degree" by color

(now all the color is bule in the following picture)

now I get a course_heat_num from the server but I have no idea how to use it cause I want the "cool color"(like #cc00ff) represent small course_heat_num and "warm color"(like #ff0000) represent the big number

I don't know the function or the variation in the chang from the cool color to the warm color(BTW:not from #000000 to #FFFFFF)

You might want to look at HSL colours in the CSS3 Colour Module.

It allows you to express colours as Hue, Saturation, and Lightness instead of RGB values. In your example, blue would be hsl(0, 100%, 50%) but red would be hsl(249, 100%, 50%). You can vary between 0 and 249 for the hue parameter.

To get an idea of what the colours look like, try the HSL Color Picker.

You should check out the wiki, here are a number of ways for you to go.

Pick a technique, and calculate the proper color, it should be nice.