The following article contains instructions for sites built on HubSpot's Classic Content Management System (CMS).
To make a global font size change please use the following instructions:
Navigate to Content > Content Settings.
Within the Content Settings page, select Website Template.
Click on the Advanced Color and Font Selection tab.
Edit the Base Font Size accordingly. Once finished, click on the Save button located at the bottom of the page.
Related Article: Are you using HubSpot's COS platform? Visit our COS tutorial for changing colors and fonts in website pages.