how to add style to head of different pages

I create “test cases” to illustrate various web coding practices. I would like to use a custom page template for writing the test cases. The unique need I have is to include a style block in the head of each page … and that style block is different from page to page.

I think I need two parts, a way to edit an extra textarea to collect the style information, and a way to call that textarea into my custom template.