Switch to Appearance > Breakpoints
You are presented with an overview of all currently defined breakpoints in your installation.
Those breakpoints each consist of three fields. Those are the breakpoints slug, the title and the value from which on it will be active.
The most important field is the min-width value.
Let's set up those breakpoints to be suitable for a smartphone, a table with a screen resolution of 768px and desktop computers with resolutions of 1024px and above.
Confirm changes with a click on Save Changes.
Notice the message informing you of the successful file generation – this is important for empty to work correctly.
Pro users are able to add as many breakpoints as they want to the existing three default ones.
Just enter a unique slug and press Add Breakpoint.
Fill out the remaining info and …
… confirm your changes with a click on Save Changes.