Baseline allows you to create 3 color schemes that can be applied to sections across your site. Each color scheme includes the following colours:
You can apply a color scheme to a section by selecting it in the Color scheme drop down.
Example: a rich text section with a different color scheme applied.
On template pages, you can also choose to override the header and footer color scheme with the color scheme of that page template. To do this, just check the checkbox labelled Use this color scheme for header and footer.
As an example, below on the left is an article template with this checkbox unchecked, on the right is with this checkbox checked. As you can see header takes on the "dark" color scheme: