Context
You can use contextual classes like .btn-primary to give each buton a unique style.
Outline
Replace the default modifier classes with the .btn-outline-* ones to remove all background images and colors on any button.
Size
Fancy larger or smaller buttons? Add .btn-lg or .btn-sm for additional sizes.
Block
Create block level buttons — those that span the full width of a parent—by adding .btn-block.