/* ==========================================================================
   Button
   ========================================================================== */

.btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  height: 40px;
  padding: 0 var(--space-4);
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  font-family: inherit;
  font-size: var(--font-size-body);
  font-weight: var(--font-weight-medium);
  white-space: nowrap;
  user-select: none;
  transition: background-color var(--transition-fast), border-color var(--transition-fast),
    color var(--transition-fast), filter var(--transition-fast);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

/* Sizes */
.btn--sm {
  height: 32px;
  padding: 0 var(--space-3);
  font-size: var(--font-size-small);
}

.btn--lg {
  height: 48px;
  padding: 0 var(--space-5);
}

.btn--icon {
  width: 40px;
  padding: 0;
}

.btn--icon.btn--sm {
  width: 32px;
}

.btn--icon.btn--lg {
  width: 48px;
}

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

/* Variants */
.btn--primary {
  background-color: var(--color-primary);
  color: #ffffff;
}
.btn--primary:hover:not(:disabled) {
  background-color: var(--color-primary-hover);
}

.btn--secondary {
  background-color: var(--color-surface-secondary);
  color: var(--color-text-primary);
  border-color: var(--color-border);
}
.btn--secondary:hover:not(:disabled) {
  background-color: var(--color-border);
}

.btn--outline {
  background-color: transparent;
  color: var(--color-text-primary);
  border-color: var(--color-border);
}
.btn--outline:hover:not(:disabled) {
  background-color: var(--color-surface-secondary);
}

.btn--ghost {
  background-color: transparent;
  color: var(--color-text-secondary);
}
.btn--ghost:hover:not(:disabled) {
  background-color: var(--color-surface-secondary);
  color: var(--color-text-primary);
}

.btn--danger {
  background-color: var(--color-danger);
  color: #ffffff;
}
.btn--danger:hover:not(:disabled) {
  filter: brightness(0.92);
}

.btn--success {
  background-color: var(--color-success);
  color: #ffffff;
}
.btn--success:hover:not(:disabled) {
  filter: brightness(0.92);
}

/* Loading state — label/icon hide via visibility so layout size never jumps */
.btn--loading {
  pointer-events: none;
}

.btn--loading .btn-label,
.btn--loading .icon {
  visibility: hidden;
}

.btn--loading::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 16px;
  height: 16px;
  margin: -8px 0 0 -8px;
  border: 2px solid currentColor;
  border-right-color: transparent;
  border-radius: 50%;
  animation: btn-spin 600ms linear infinite;
}

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

@media (prefers-reduced-motion: reduce) {
  .btn--loading::after {
    animation-duration: 1.2s;
  }
}