Just add the base btn btn-primaryto any <button>
btn btn-primary
<button>
Just add the base btn btn-outline-*to any <button>
btn btn-outline-*
Just add the class btn-lg or btn-sm or btn-blockto any btnclass.
btn-lg or btn-sm or btn-block
btn
Just add the class active or disabledto any btnclass.
active or disabled