Dimensions
Size is one independent axis — .btn-xs, .btn-sm, default (no class), .btn-lg, .btn-xl — combinable with any intent/style class.
.btn-xsExtra small.btn-smSmall.btn (default)Medium.btn-lgLarge.btn-xlExtra largeSize is one independent axis — .btn-xs, .btn-sm, default (no class), .btn-lg, .btn-xl — combinable with any intent/style class.
.btn-xsExtra small.btn-smSmall.btn (default)Medium.btn-lgLarge.btn-xlExtra large