You can use a custom domain instead of
your-project.gitbook.io . See the dedicated page for more info:
Having a logo for your project is the first step to make your reader feel at home. You can add one from the General Settings of your project.
The primary color of your project will be used for details in your documentation. Links, for example, use the primary color. It should be the same dominant color used in your logo, or a good complementary color, and it should have enough contrast with white background. Avoid light colors such as yellow. Pick a primary color in your space's General Settings.
Header links are typically used to link to your other sites, such as your project's homepage, a forum, or a GitHub repository. You can add them from the General Settings of your space.