Sizes · lg 36 · md 32 · sm 28 · xs 24 — letter-spacing tracks size
With icon · secondary pattern
States · hover · focus · disabled · loading
Accessibility floor. White-on-green and white-on-red sit at 3.2–3.9 contrast — an accepted APCA Lc 60+ contract (medium-weight uppercase labels, tagged data-contrast-contract="apca"), not a WCAG 4.5:1 pass. Never use btn-sm or btn-xs for btn-success, btn-danger, or btn-info. For tight rows use btn-primary (yellow on black = 14:1 AAA at any size) or btn-default. See the Accessibility audit preview.