Based on the breakpoints you created empty will generate individual column classes for layouts with a maximum of 12 columns floating horizontally next to each other.
For example if you've set up a breakpoint with the slug
sm the following classes will be triggered whenever the viewport is active:
In addition to the classes which determine how many columns a certain content will use, classes will be created to offset content parts from the left for a certain amount of columns.
Following the example above those classes will be:
There is one more class that may be added to any container with a column class applied which is
.single. Add it to a column and the column won't have any margin applied underneath it.