/* ── Buttons ─────────────────────────────────────────────── */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.875rem 2rem;
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: var(--fw-medium);
  letter-spacing: var(--ls-widest);
  text-transform: uppercase;
  white-space: nowrap;
  cursor: pointer;
  border: 1px solid transparent;
  border-radius: var(--radius-xs);
  transition:
    background-color var(--t-fast) var(--ease),
    border-color var(--t-fast) var(--ease),
    color var(--t-fast) var(--ease),
    opacity var(--t-fast) var(--ease);
  user-select: none;
  -webkit-tap-highlight-color: transparent;
  text-decoration: none;
}

.btn:disabled,
.btn.is-disabled {
  opacity: 0.4;
  pointer-events: none;
}

.btn.is-loading {
  pointer-events: none;
  position: relative;
  color: transparent;
}

.btn.is-loading::after {
  content: '';
  position: absolute;
  width: 1rem;
  height: 1rem;
  border: 1.5px solid currentColor;
  border-top-color: transparent;
  border-radius: 50%;
  animation: btn-spin 0.6s linear infinite;
}

@keyframes btn-spin {
  to { transform: rotate(360deg); }
}

/* Variants */

.btn--primary {
  background: var(--color-ink);
  border-color: var(--color-ink);
  color: var(--color-paper);
}

.btn--primary:hover {
  background: var(--color-warm);
  border-color: var(--color-warm);
  opacity: 1;
}

.btn--primary.is-loading { color: transparent; }
.btn--primary.is-loading::after { border-color: var(--color-paper); border-top-color: transparent; }

.btn--outline {
  background: transparent;
  border-color: var(--color-ink);
  color: var(--color-ink);
}

.btn--outline:hover {
  background: var(--color-ink);
  color: var(--color-paper);
  opacity: 1;
}

.btn--ghost {
  background: transparent;
  border-color: transparent;
  color: var(--color-ink);
}

.btn--ghost:hover { background: var(--color-canvas); opacity: 1; }

.btn--white {
  background: var(--color-paper);
  border-color: var(--color-paper);
  color: var(--color-ink);
}

.btn--white:hover { background: var(--color-canvas); opacity: 1; }

.btn--accent {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-paper);
}

.btn--accent:hover { background: var(--color-accent-dark); border-color: var(--color-accent-dark); opacity: 1; }

/* Sizes */

.btn--sm {
  padding: 0.625rem 1.25rem;
  font-size: calc(var(--text-xs) * 0.9);
}

.btn--lg {
  padding: 1.125rem 2.5rem;
  font-size: var(--text-sm);
}

.btn--full {
  width: 100%;
}

/* Icon-only button */

.btn--icon {
  padding: 0.625rem;
  border-radius: var(--radius-sm);
}

/* Quantity stepper */

.qty-stepper {
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

.qty-stepper__btn {
  width: 2.25rem;
  height: 2.25rem;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--text-lg);
  color: var(--color-ink);
  transition: opacity var(--t-fast);
}

.qty-stepper__btn:hover { opacity: 0.5; }

.qty-stepper__value {
  min-width: 2.5rem;
  text-align: center;
  font-size: var(--text-sm);
  font-weight: var(--fw-medium);
  letter-spacing: var(--ls-wider);
  border-inline: 1px solid var(--border);
  padding-block: 0.5rem;
}