A breakpoint is the point at which the page content, layout and design in general adapts to the size of the viewport (screen, browser window). Generally, you can set different styles for these breakpoints.
There are two editing modes in HubSpot's page editor: Desktop and Mobile. We have linked the Mobile mode to our Small screens breakpoint.
Here are all three breakpoints in Act3:
Our theme follows a desktop-first approach, to keep a consistency with the HubSpot layout and tools. That means, for example, if you set your text alignment on large screens, but don't specify it for medium or small screens, it will inherit the same alignment for those screen sizes as well.
Screens smaller than 1140px.
Screens smaller than 768px