@layer components {

  /* ── Base structure ──────────────────────────────────────────────── */

  .btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    font-family: var(--font-sans);
    font-size: var(--text-base);
    font-weight: 500;
    line-height: var(--leading-normal);
    min-height: 32px;
    padding: var(--space-2) var(--space-4);
    border-radius: 0;
    cursor: pointer;
    text-decoration: none;
    transition:
      background-color var(--duration-normal) ease-out,
      border-color var(--duration-normal) ease-out,
      color var(--duration-normal) ease-out;
  }

  /* ── Icon sizing ─────────────────────────────────────────────────── */

  .btn > svg {
    width: var(--icon-sm);
    height: var(--icon-sm);
    flex-shrink: 0;
  }

  /* ── Primary ─────────────────────────────────────────────────────── */

  .btn-primary {
    background-color: var(--color-accent-base);
    color: var(--color-surface-primary);
    border: none;
  }

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

  .btn-primary:active {
    background-color: var(--color-accent-hover);
    filter: brightness(0.9);
    transition: none;
  }

  /* ── Secondary ───────────────────────────────────────────────────── */

  .btn-secondary {
    background-color: var(--color-surface-primary);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border-default);
  }

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

  .btn-secondary:active {
    background-color: var(--color-surface-tertiary);
    transition: none;
  }

  /* ── Ghost ───────────────────────────────────────────────────────── */

  .btn-ghost {
    background-color: transparent;
    color: var(--color-text-secondary);
    border: none;
  }

  .btn-ghost:hover {
    background-color: var(--color-surface-secondary);
  }

  .btn-ghost:active {
    background-color: var(--color-surface-tertiary);
    transition: none;
  }

  /* ── Focus ───────────────────────────────────────────────────────── */

  .btn:focus-visible {
    outline: 2px solid var(--color-accent-base);
    outline-offset: 2px;
  }

  /* ── Disabled ────────────────────────────────────────────────────── */

  .btn:disabled,
  .btn[aria-disabled="true"] {
    opacity: 0.4;
    cursor: not-allowed;
    pointer-events: none;
  }

  /* ── Loading ─────────────────────────────────────────────────────── */

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

  .btn.is-loading > * {
    visibility: hidden;
  }

  .btn.is-loading::after {
    content: "";
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: inherit;
    animation: btn-pulse 1s ease-in-out infinite;
  }

  @keyframes btn-pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
  }

  @media (prefers-reduced-motion: reduce) {
    @keyframes btn-pulse {
      0%, 100% { opacity: 1; }
      50% { opacity: 0.6; }
    }
  }
}