All buttons are outline by default.
If You want larger or smaller buttons You can add .btn-lg, .btn-sm, or .btn-xs class.
This is a group of buttons, ideal for situation where many actions are related to same element.
To buttons with any color or any size you can add extra icon on the left or the right side.
You can also add .btn-square class to squared buttons.
You can also add .btn-block class to block feature in your links or buttons.
You can also add .btn-rounded class to round buttons.
Use the .fa-spin class to get any icon to rotate, and use .fa-pulse to have it rotate with 8 steps.