/* ============================================================================
   § 27. RESPONSIVE — TABLET (max-width: 768px)
   ============================================================================ */

@media (max-width: 768px) {

  /* ── Navigation ── */
  .nav-toggle {
    display: flex;
  }

  .mobile-only {
    display: flex !important;
  }

  .top-bar__nav {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: var(--top-bar-height);
    left: 0;
    right: 0;
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    z-index: 999;
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    transition: max-height 0.4s cubic-bezier(0.25, 0.1, 0.25, 1),
      opacity 0.3s ease;
  }

  .top-bar__nav--open {
    max-height: 400px;
    opacity: 1;
  }

  .top-bar__nav .nav-item {
    padding: 14px 24px;
    height: auto;
    border-bottom: 1px solid var(--color-border-light);
    opacity: 0;
    transform: translateY(-8px);
    transition: opacity 0.3s ease, transform 0.3s ease;
  }

  .top-bar__nav--open .nav-item {
    opacity: 1;
    transform: translateY(0);
  }

  .top-bar__nav--open .nav-item:nth-child(1) { transition-delay: 0.05s; }
  .top-bar__nav--open .nav-item:nth-child(2) { transition-delay: 0.1s; }
  .top-bar__nav--open .nav-item:nth-child(3) { transition-delay: 0.15s; }
  .top-bar__nav--open .nav-item:nth-child(4) { transition-delay: 0.2s; }
  .top-bar__nav--open .nav-item:nth-child(5) { transition-delay: 0.25s; }
  .top-bar__nav--open .nav-item:nth-child(6) { transition-delay: 0.3s; }
  .top-bar__nav--open .nav-item:nth-child(7) { transition-delay: 0.35s; }

  .top-bar__nav .nav-item:hover,
  .top-bar__nav .nav-item--active {
    background-color: var(--color-surface);
  }

  .top-bar__nav .nav-item:last-child {
    border-bottom: none;
  }

  /* ── Content Grid ── */
  .content-grid {
    flex-direction: column;
    gap: 32px;
  }

  /* ── Sidebar ── */
  .sidebar {
    display: none;
  }

  /* ── Search overlay: closer to top on mobile ── */
  .search-overlay {
    padding-top: 60px;
  }

  /* ── Search kbd shortcut ── */
  .search-kbd {
    display: none;
  }

  /* ── Compact Grid ── */
  .compact-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  /* ── List Post Card Thumbnail ── */
  .post-card__thumb {
    width: 120px;
    height: auto;
    aspect-ratio: 3 / 2;
  }

  /* ── Article Title ── */
  .article-title {
    font-size: 1.8rem;
  }

  /* ── Post Nav ── */
  .post-nav {
    grid-template-columns: 1fr;
  }

  .post-nav-card {
    height: 100px;
  }

  .post-nav-card--empty {
    height: 60px;
  }

  .post-nav-card__img {
    width: 90px;
  }

  /* ── Hero Section ── */
  .hero-section {
    height: 280px;
  }

  .hero-content {
    bottom: 24px;
    padding: 0 16px;
  }

  .hero-title {
    font-size: 1.5rem;
  }

  /* ── Header Spacer (collapsed — no section bar visible) ── */
  .main-content-wrapper {
    margin-top: var(--top-bar-height);
  }

  /* ── Container padding ── */
  .container {
    padding: 0 16px;
  }

  .content-grid {
    padding: 0 16px;
  }

  /* ── Page layout ── */
  .page-container {
    padding: 0 16px 60px;
  }

  .article-container {
    padding: 40px 16px 60px;
  }

  .page-header {
    padding-top: 40px;
  }

  /* ── Archive List ── */
  .archive-year {
    font-size: 0.9rem;
    margin-top: 36px;
  }

  .archive-item {
    gap: 12px;
    padding: 12px 0;
  }

  .archive-item__date {
    width: 90px;
    font-size: 12px;
  }

  .archive-item__title {
    font-size: 14.5px;
  }

  /* ── Footer ── */
  .footer-inner {
    padding: 0 16px;
  }
}


/* ============================================================================
   § 28. RESPONSIVE — SMALL MOBILE (max-width: 480px)
   ============================================================================ */

@media (max-width: 480px) {

  /* ── Compact Grid: single column ── */
  .compact-grid {
    grid-template-columns: 1fr;
  }

  /* ── List Post Card: stack vertically ── */
  .post-card--list {
    flex-direction: column;
    gap: 16px;
  }

  .post-card--list .post-card__thumb-link {
    order: -1;
    width: 100%;
  }

  .post-card--list .post-card__thumb {
    width: 100%;
    height: auto;
    aspect-ratio: 16 / 9;
    order: -1;
  }

  /* ── Hero ── */
  .hero-content {
    bottom: 20px;
    padding: 0 16px;
  }

  .hero-title {
    font-size: 1.3rem;
  }

  /* ── Article ── */
  .article-title {
    font-size: 1.6rem;
  }

  .article-content {
    font-size: 16px;
  }

  /* ── Error Page ── */
  .error-code {
    font-size: 5rem;
  }

  /* ── Friends Grid ── */
  .links-grid {
    grid-template-columns: 1fr;
  }

  /* ── Page title ── */
  .page-title {
    font-size: 1.6rem;
  }
}