Horizontal Alignment
Horizontal alignment controls how the columns are arranged in a particular row. This setting is applied to the .row.
justify-content-center
This will justify all bootstrap columns in the center of the container.
Example: Any columns added past the 12th will be wrapped, and also justified center. Here is an example of 13.
2/12
1/12
10/12
1/2
1/2
12/12
1/12
Auto sized. No width was specified, so it will automatically grow to fit the row.
1/12
auto grow column (no width set)