You can customize the style of your content using Themes. Themes let you adjust elements like colors, footer, logo, and more to suit your preferences. To edit or create a design theme, click on Publisher in the document editor. 

Then, under the Themes section, you can either modify your current theme or create a new one.

In the theme editor, you can modify the elements of your theme using the left sidebar:

On the right side, you can preview your theme applied to sample content.