Buttons are components that can be formed using existing core classes and a couple of specific classes for colors only.
button
button.p-xs.r-s.border
Buttons can also be colored in order to give direct visual feedback on their intended action by simply giving them another class.
button.p-xs.r-s.border.btn-primary
button.p-xs.r-s.border.btn-success
button.p-xs.r-s.border.btn-warning
button.p-xs.r-s.border.btn-error