.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  padding: var(--space-2) var(--space-4);
  font: inherit;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: background-color var(--transition-fast), border-color var(--transition-fast),
    transform var(--transition-fast), box-shadow var(--transition-fast);
}

.btn:active {
  transform: translateY(1px);
}

.btn:disabled,
.btn[aria-disabled="true"] {
  cursor: not-allowed;
  opacity: 0.5;
  transform: none;
}

.btn-primary {
  background: var(--color-primary);
  color: var(--color-primary-text);
}

.btn-primary:hover:not(:disabled) {
  box-shadow: var(--shadow-sm);
  filter: brightness(1.08);
}

.btn-secondary {
  background: var(--color-secondary);
  color: var(--color-secondary-text);
}

.btn-secondary:hover:not(:disabled) {
  filter: brightness(0.96);
}

@media (prefers-color-scheme: dark) {
  .btn-secondary:hover:not(:disabled) {
    filter: brightness(1.15);
  }
}

.btn-danger {
  background: var(--color-danger);
  color: var(--color-danger-text);
}

.btn-danger:hover:not(:disabled) {
  filter: brightness(1.08);
}

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

.btn-outline:hover:not(:disabled) {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.btn-sm {
  padding: var(--space-1) var(--space-3);
  font-size: 0.875rem;
}

.btn-lg {
  padding: var(--space-3) var(--space-6);
  font-size: 1.05rem;
}