Global Theme Styles - Setting up theme settings.
The first step should be to setup brand colors, fonts and other styles at the ready. This is going to save you a lot of time and keep your site cohesive.
Here are the steps to do so:
Create a new page and in the page editor, navigate to the Design tab.
Select “edit theme settings.
Set all of your theme settings to determine your website’s styles.
Set your logo, spacing, typography, buttons etc as well.
More info & Official guide : https://knowledge.hubspot.com/website-pages/edit-your-global-theme-settings