You can change the color scheme for your common pages to be light or dark. The color scheme will apply to all your account and checkout pages. Your Home, Catalog, Custom, and Landing pages will not be changed by the color scheme. Those pages are affected by your chosen theme.
To change it, navigate to Customization and Click Customize. Next to the Color Scheme area, choose between the Light or Dark scheme. Then scroll down and Save your changes.
When you choose the Light scheme, the pages affected by this scheme will display like the following:
When you choose the Dark scheme, the pages affected by this scheme will display like the following:
To view what each color scheme looks like on your site, select one of the schemes and view your storefront.