/* ========== Reset ========== */
    *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

    ::selection {
      background: rgba(206,0,0,0.15);
      color: var(--color-text);
    }

    :root {
      /* bullstory brand color palette */
      --color-bg: #fbfbfd;
      --color-surface: #ffffff;
      --color-surface-elevated: rgba(255,255,255,0.82);
      --color-text: #1d1d1f;
      --color-text-secondary: #6e6e73;
      --color-text-tertiary: #86868b;
      --color-primary: #CE0000;
      --color-primary-hover: #B80000;
      --color-primary-text-sm: #A80000; /* #CE0000 darker variant for small text (≤12px) — WCAG AA 7:1+ contrast on white */
      --color-primary-bg: rgba(206,0,0,0.06);
      --color-accent: #1d1d1f;
      --color-border: rgba(0,0,0,0.06);
      --color-border-strong: rgba(0,0,0,0.1);
      --color-border-glass: rgba(255,255,255,0.5);
      --color-sale: #bf4800;
      --color-success: #248a3d;

      --radius-xl: 24px;
      --radius-lg: 20px;
      --radius-md: 14px;
      --radius-sm: 10px;
      --radius-xs: 6px;
      --radius-pill: 999px;

      --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
      --shadow-card: 0 1px 3px rgba(0,0,0,0.04), 0 4px 24px rgba(0,0,0,0.04);
      --shadow-card-hover: 0 8px 36px rgba(0,0,0,0.1), 0 2px 8px rgba(0,0,0,0.04);
      --shadow-elevated: 0 20px 60px rgba(0,0,0,0.12), 0 8px 20px rgba(0,0,0,0.06);

      --font-en: 'Pretendard Variable', Pretendard, -apple-system, BlinkMacSystemFont, sans-serif;
      --font-kr: 'Pretendard Variable', Pretendard, -apple-system, BlinkMacSystemFont, sans-serif;
      --font: var(--font-kr);

      --page-max: 1080px;
      --page-pad: 24px;

      --sp-xs: 4px;
      --sp-sm: 8px;
      --sp-md: 12px;
      --sp-lg: 16px;
      --sp-xl: 20px;
      --sp-2xl: 24px;
      --sp-3xl: 32px;
      --sp-4xl: 40px;
      --sp-5xl: 48px;
      --sp-6xl: 64px;
      --sp-7xl: 80px;
      --sp-8xl: 100px;
      --sp-9xl: 120px;
    }

    /* ========== Dark Mode ========== */
    [data-theme="dark"] {
      --color-bg: #1a1a1a;
      --color-surface: #2a2a2a;
      --color-surface-elevated: rgba(42,42,42,0.82);
      --color-text: #f5f5f5;
      --color-text-secondary: #a0a0a0;
      --color-text-tertiary: #666666;
      --color-primary: #FF3333;
      --color-primary-hover: #FF4D4D;
      --color-primary-text-sm: #FF4D4D;
      --color-primary-bg: rgba(255,51,51,0.1);
      --color-accent: #f5f5f5;
      --color-border: rgba(255,255,255,0.08);
      --color-border-strong: rgba(255,255,255,0.15);
      --color-border-glass: rgba(255,255,255,0.1);
      --color-sale: #FF6B35;
      --color-success: #34C759;

      --shadow-card: 0 2px 8px rgba(0,0,0,0.2), 0 0 1px rgba(0,0,0,0.3);
      --shadow-card-hover: 0 8px 30px rgba(0,0,0,0.3);
      --shadow-elevated: 0 20px 60px rgba(0,0,0,0.4);

      color-scheme: dark;
    }

    [data-theme="dark"] ::selection {
      background: rgba(255,51,51,0.25);
    }

    [data-theme="dark"] .header {
      background: rgba(26,26,26,0.85);
    }

    [data-theme="dark"] .header-search input {
      background: rgba(255,255,255,0.08);
    }

    [data-theme="dark"] .header-search input:focus {
      background: rgba(255,255,255,0.12);
      box-shadow: 0 0 0 3px rgba(255,51,51,0.15);
    }

    [data-theme="dark"] .category-bar {
      background: rgba(255,255,255,0.06);
    }

    [data-theme="dark"] .category-tag.active {
      background: var(--color-surface);
    }

    [data-theme="dark"] .book-card-cover {
      background: #222;
    }

    [data-theme="dark"] .detail-cover {
      background: linear-gradient(160deg, #222 0%, #1a1a1a 100%);
    }

    [data-theme="dark"] .detail-price-section {
      background: rgba(255,255,255,0.04);
    }

    [data-theme="dark"] .modal-overlay {
      background: rgba(0,0,0,0.55);
    }

    [data-theme="dark"] .btn-google {
      background: var(--color-surface);
      border-color: rgba(255,255,255,0.15);
    }

    [data-theme="dark"] .btn-google:hover {
      background: rgba(255,255,255,0.08);
      border-color: rgba(255,255,255,0.25);
    }

    [data-theme="dark"] .nav-link:hover {
      background: rgba(255,255,255,0.06);
    }

    [data-theme="dark"] .mobile-menu-btn:hover {
      background: rgba(255,255,255,0.06);
    }

    [data-theme="dark"] .mobile-nav-drawer {
      background: #1e1e1e;
    }

    [data-theme="dark"] .mobile-nav-overlay {
      background: rgba(0,0,0,0.5);
    }

    [data-theme="dark"] .mobile-nav-link:hover {
      background: rgba(255,255,255,0.06);
    }

    [data-theme="dark"] .mobile-nav-search input {
      background: rgba(255,255,255,0.08);
    }

    [data-theme="dark"] .mobile-nav-search input:focus {
      background: rgba(255,255,255,0.12);
      box-shadow: 0 0 0 3px rgba(255,51,51,0.15);
    }

    [data-theme="dark"] .mobile-nav-close:hover {
      background: rgba(255,255,255,0.08);
    }

    [data-theme="dark"] .modal-close:hover {
      background: rgba(255,255,255,0.08);
    }

    [data-theme="dark"] .toast {
      background: rgba(245,245,245,0.95);
      color: #1a1a1a;
    }

    [data-theme="dark"] .toast.error {
      background: #ff3b30;
      color: #fff;
    }

    [data-theme="dark"] .toast.success {
      background: var(--color-success);
      color: #fff;
    }

    [data-theme="dark"] .scroll-top-btn {
      background: rgba(42,42,42,0.85);
      color: var(--color-text);
      box-shadow: 0 2px 12px rgba(0,0,0,0.3), 0 0 0 0.5px rgba(255,255,255,0.08);
    }

    [data-theme="dark"] .scroll-top-btn:hover {
      background: rgba(50,50,50,0.95);
      box-shadow: 0 6px 20px rgba(0,0,0,0.4), 0 0 1px rgba(255,255,255,0.1);
    }

    [data-theme="dark"] .purchase-item:hover {
      background: rgba(255,255,255,0.03);
    }

    [data-theme="dark"] .purchase-item-cover {
      background: #222;
    }

    [data-theme="dark"] .skeleton-cover,
    [data-theme="dark"] .skeleton-line,
    [data-theme="dark"] .skeleton-detail-cover,
    [data-theme="dark"] .skeleton-purchase-cover {
      background: linear-gradient(90deg, #2a2a2a 25%, #333 50%, #2a2a2a 75%);
      background-size: 200% 100%;
    }

    [data-theme="dark"] :focus-visible {
      outline-color: rgba(255,51,51,0.5);
    }

    /* ========== Theme Toggle Button ========== */
    .theme-toggle {
      width: 36px;
      height: 36px;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 50%;
      transition: background 0.2s, transform 0.2s;
      flex-shrink: 0;
      color: var(--color-text-secondary);
    }

    .theme-toggle:hover {
      background: rgba(0,0,0,0.06);
      color: var(--color-text);
    }

    [data-theme="dark"] .theme-toggle:hover {
      background: rgba(255,255,255,0.08);
    }

    .theme-toggle:active {
      transform: scale(0.9);
    }

    .theme-toggle svg {
      width: 18px;
      height: 18px;
      transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    }

    .theme-toggle:hover svg {
      transform: rotate(15deg);
    }

    .theme-toggle .icon-sun,
    .theme-toggle .icon-moon { display: none; }

    /* 라이트 모드: 달 아이콘 표시 (다크로 전환 의미) */
    .theme-toggle .icon-moon { display: block; }
    .theme-toggle .icon-sun { display: none; }

    [data-theme="dark"] .theme-toggle .icon-moon { display: none; }
    [data-theme="dark"] .theme-toggle .icon-sun { display: block; }

    html { scroll-behavior: smooth; color-scheme: light; }
    [data-theme="dark"] { color-scheme: dark; }

    body {
      font-family: var(--font);
      background: var(--color-bg);
      color: var(--color-text);
      line-height: 1.5;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
      text-rendering: optimizeLegibility;
      font-feature-settings: 'kern' 1;
    }

    /* 노이즈 텍스처 제거 — 미니멀 디자인 */

    a { color: inherit; text-decoration: none; }
    button { font-family: inherit; cursor: pointer; border: none; background: none; }
    img { display: block; max-width: 100%; }

    .container {
      max-width: var(--page-max);
      margin: 0 auto;
      padding: 0 var(--page-pad);
    }

    /* ========== Fade-in Animation ========== */
    .fade-in {
      opacity: 0;
      transform: translateY(12px);
      transition: opacity 0.5s cubic-bezier(0.16, 1, 0.3, 1),
                  transform 0.5s cubic-bezier(0.16, 1, 0.3, 1);
    }

    .fade-in.visible {
      opacity: 1;
      transform: translateY(0);
    }

    /* ========== Header (Apple-style glassmorphism) ========== */
    .header {
      position: sticky;
      top: 0;
      z-index: 100;
      background: rgba(251,251,253,0.78);
      backdrop-filter: saturate(200%) blur(24px);
      -webkit-backdrop-filter: saturate(200%) blur(24px);
    }

    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 48px;
      gap: var(--sp-xl);
    }

    .logo {
      font-family: var(--font-en);
      font-size: 17px;
      font-weight: 800;
      letter-spacing: -0.6px;
      color: var(--color-text);
      flex-shrink: 0;
      transition: opacity 0.2s;
    }

    .logo:hover { opacity: 0.7; }

    .logo .accent {
      color: var(--color-primary);
    }

    .header-nav {
      display: flex;
      align-items: center;
      gap: var(--sp-xs);
      flex-shrink: 0;
    }

    .nav-link {
      padding: var(--sp-sm) var(--sp-md);
      font-size: 13px;
      font-weight: 500;
      color: var(--color-text-secondary);
      border-radius: var(--radius-pill);
      transition: color 0.2s, background 0.2s;
      letter-spacing: -0.1px;
    }

    .nav-link:hover {
      color: var(--color-text);
      background: rgba(0,0,0,0.03);
    }

    .nav-link.active {
      color: var(--color-text);
      font-weight: 600;
    }

    .nav-link.cta {
      color: var(--color-primary);
      font-weight: 600;
    }

    .nav-link.cta:hover {
      background: var(--color-primary-bg);
    }

    .nav-user {
      display: flex;
      align-items: center;
      gap: var(--sp-sm);
    }

    .nav-avatar {
      width: 28px;
      height: 28px;
      border-radius: 50%;
      overflow: hidden;
      background: var(--color-border);
    }

    .nav-avatar img {
      width: 100%;
      height: 100%;
      object-fit: cover;
    }

    .nav-username {
      font-size: 13px;
      font-weight: 500;
      color: var(--color-text);
    }

    /* ========== Search Bar ========== */
    .header-search {
      flex: 1;
      max-width: 400px;
      position: relative;
    }

    .header-search input {
      width: 100%;
      height: 34px;
      padding: 0 var(--sp-lg) 0 34px;
      border: none;
      border-radius: var(--radius-pill);
      font-size: 13px;
      font-family: var(--font);
      background: rgba(0,0,0,0.04);
      color: var(--color-text);
      outline: none;
      transition: background 0.2s, box-shadow 0.3s;
    }

    .header-search input::placeholder {
      color: var(--color-text-tertiary);
    }

    .header-search input:focus {
      background: rgba(0,0,0,0.06);
      box-shadow: 0 0 0 3px rgba(206,0,0,0.1);
    }

    .header-search .search-icon {
      position: absolute;
      left: var(--sp-md);
      top: 50%;
      transform: translateY(-50%);
      width: 14px;
      height: 14px;
      color: var(--color-text-tertiary);
    }

    .header-search .search-icon svg {
      width: 100%;
      height: 100%;
    }

    /* ========== Views ========== */
    .view { display: none; }
    .view.active {
      display: block;
      animation: viewFadeIn 0.4s cubic-bezier(0.16, 1, 0.3, 1) both;
    }

    @keyframes viewFadeIn {
      from { opacity: 0; transform: translateY(10px); }
      to { opacity: 1; transform: translateY(0); }
    }

    /* Staggered children entrance within views */
    .view.active > .fade-in:nth-child(1) { transition-delay: 0s; }
    .view.active > .fade-in:nth-child(2) { transition-delay: 0.06s; }
    .view.active > .fade-in:nth-child(3) { transition-delay: 0.12s; }
    .view.active > .fade-in:nth-child(4) { transition-delay: 0.18s; }

    /* ========== Hero Section ========== */
    .hero {
      padding: var(--sp-9xl) 0 var(--sp-8xl);
      text-align: center;
      position: relative;
      overflow: hidden;
    }

    /* hero 그라디언트/애니메이션 제거 — 미니멀 디자인 */

    .hero-eyebrow {
      display: inline-flex;
      align-items: center;
      gap: var(--sp-sm);
      font-size: 12px;
      font-weight: 600;
      color: var(--color-primary-text-sm);
      margin-bottom: var(--sp-2xl);
      letter-spacing: 1.5px;
      text-transform: uppercase;
      font-family: var(--font-en);
      padding: var(--sp-sm) var(--sp-lg);
      background: var(--color-primary-bg);
      border-radius: var(--radius-pill);
    }

    .hero h1 {
      font-size: 68px;
      font-weight: 700;
      letter-spacing: -3.5px;
      line-height: 1.15;
      margin-bottom: var(--sp-3xl);
      color: var(--color-text);
    }

    .hero p {
      font-size: 20px;
      font-weight: 400;
      color: var(--color-text-secondary);
      line-height: 1.6;
      letter-spacing: -0.4px;
      max-width: 460px;
      margin: 0 auto;
    }

    .hero-cta {
      display: inline-flex;
      align-items: center;
      gap: var(--sp-sm);
      margin-top: var(--sp-4xl);
      padding: var(--sp-lg) var(--sp-3xl);
      font-size: 16px;
      font-weight: 600;
      color: #fff;
      background: var(--color-primary);
      border-radius: var(--radius-pill);
      transition: transform 0.25s cubic-bezier(0.16, 1, 0.3, 1),
                  background 0.2s ease,
                  box-shadow 0.25s cubic-bezier(0.16, 1, 0.3, 1);
      letter-spacing: -0.2px;
      will-change: transform;
    }

    .hero-cta:hover {
      background: var(--color-primary-hover);
      transform: scale(1.03);
    }

    .hero-cta:active {
      transform: scale(0.97);
      transition-duration: 0.1s;
    }

    .hero-cta svg {
      width: 16px;
      height: 16px;
      transition: transform 0.3s;
    }

    .hero-cta:hover svg {
      transform: translateY(2px);
    }

    /* ========== Category Filter ========== */
    .category-section {
      padding-bottom: var(--sp-5xl);
    }

    .category-bar {
      display: flex;
      gap: var(--sp-xs);
      overflow-x: auto;
      -webkit-overflow-scrolling: touch;
      scrollbar-width: none;
      padding: var(--sp-xs);
      background: rgba(0,0,0,0.04);
      border-radius: var(--radius-pill);
      width: fit-content;
    }

    .category-bar::-webkit-scrollbar { display: none; }

    .category-tag {
      padding: var(--sp-sm) var(--sp-xl);
      font-size: 13px;
      font-weight: 500;
      white-space: nowrap;
      border-radius: var(--radius-pill);
      background: transparent;
      color: var(--color-text-secondary);
      transition: color 0.2s ease,
                  background 0.2s ease,
                  transform 0.15s ease;
    }

    .category-tag:hover {
      color: var(--color-text);
    }

    .category-tag:active {
      transform: scale(0.96);
    }

    .category-tag.active {
      background: var(--color-surface);
      color: var(--color-text);
      font-weight: 600;
    }

    /* ========== Book Grid ========== */
    .book-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: var(--sp-xl);
      padding-bottom: var(--sp-8xl);
    }

    .book-card {
      background: var(--color-surface);
      border-radius: var(--radius-lg);
      overflow: hidden;
      transition: transform 0.35s cubic-bezier(0.16, 1, 0.3, 1);
      cursor: pointer;
      will-change: transform;
    }

    .book-card:hover {
      transform: translateY(-4px);
    }

    .book-card-cover {
      position: relative;
      width: 100%;
      aspect-ratio: 3/4;
      background: #f2f2f5;
      overflow: hidden;
    }

    .book-card-cover img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transition: transform 0.5s cubic-bezier(0.16, 1, 0.3, 1);
    }

    .book-card:hover .book-card-cover img {
      transform: scale(1.04);
    }

    .book-card-badge {
      position: absolute;
      top: var(--sp-md);
      left: var(--sp-md);
      padding: var(--sp-xs) var(--sp-sm);
      font-size: 10px;
      font-weight: 700;
      font-family: var(--font-en);
      background: var(--color-sale);
      color: #fff;
      border-radius: var(--radius-pill);
      letter-spacing: 0.8px;
      text-transform: uppercase;
    }

    .book-card-body {
      padding: var(--sp-xl);
    }

    .book-card-category {
      font-size: 10px;
      font-weight: 600;
      color: var(--color-primary-text-sm);
      text-transform: uppercase;
      letter-spacing: 1px;
      margin-bottom: var(--sp-sm);
      font-family: var(--font-en);
    }

    .book-card-title {
      font-size: 16px;
      font-weight: 700;
      line-height: 1.35;
      margin-bottom: var(--sp-xs);
      display: -webkit-box;
      -webkit-line-clamp: 2;
      -webkit-box-orient: vertical;
      overflow: hidden;
      letter-spacing: -0.4px;
    }

    .book-card-author {
      font-size: 13px;
      color: var(--color-text-tertiary);
      margin-bottom: var(--sp-lg);
    }

    .book-card-footer {
      display: flex;
      align-items: center;
      justify-content: space-between;
    }

    .book-card-price {
      font-family: var(--font-en);
      font-size: 18px;
      font-weight: 800;
      color: var(--color-text);
      letter-spacing: -0.5px;
      transition: color 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    }

    .book-card:hover .book-card-price {
      color: var(--color-primary);
    }

    .book-card-price .unit {
      font-family: var(--font-kr);
      font-size: 12px;
      font-weight: 500;
    }

    .book-card-price .original {
      font-size: 12px;
      color: var(--color-text-tertiary);
      text-decoration: line-through;
      font-weight: 400;
      margin-left: var(--sp-sm);
    }

    .book-card-cta {
      font-size: 12px;
      font-weight: 600;
      color: var(--color-primary-text-sm);
      display: flex;
      align-items: center;
      gap: 2px;
      opacity: 0;
      transform: translateX(-6px);
      transition: opacity 0.3s cubic-bezier(0.16,1,0.3,1),
                  transform 0.3s cubic-bezier(0.16,1,0.3,1);
    }

    .book-card:hover .book-card-cta {
      opacity: 1;
      transform: translateX(0);
    }

    /* ========== Empty State ========== */
    .empty-state {
      text-align: center;
      padding: var(--sp-8xl) var(--sp-2xl);
      color: var(--color-text-secondary);
    }

    .empty-state .icon {
      font-size: 56px;
      margin-bottom: var(--sp-xl);
      opacity: 0.25;
    }

    .empty-state h3 {
      font-size: 20px;
      font-weight: 700;
      margin-bottom: var(--sp-sm);
      color: var(--color-text);
      letter-spacing: -0.5px;
    }

    .empty-state p {
      font-size: 15px;
      color: var(--color-text-secondary);
    }

    /* ========== Detail View ========== */
    .detail-back {
      display: inline-flex;
      align-items: center;
      gap: var(--sp-sm);
      padding: var(--sp-md) 0;
      font-size: 14px;
      font-weight: 500;
      color: var(--color-primary);
      margin-top: var(--sp-2xl);
      transition: opacity 0.2s;
    }

    .detail-back:hover { opacity: 0.7; }

    .detail-back svg {
      width: 16px;
      height: 16px;
    }

    .detail-layout {
      display: grid;
      grid-template-columns: 380px 1fr;
      gap: var(--sp-6xl);
      padding: var(--sp-4xl) 0 var(--sp-9xl);
      align-items: start;
    }

    .detail-cover {
      width: 100%;
      aspect-ratio: 3/4;
      border-radius: var(--radius-xl);
      overflow: hidden;
      background: linear-gradient(160deg, #f8f8fa 0%, #ededf0 100%);
      box-shadow: 0 24px 60px rgba(0,0,0,0.14), 0 4px 16px rgba(0,0,0,0.06);
    }

    .detail-cover img {
      width: 100%;
      height: 100%;
      object-fit: cover;
    }

    .detail-info {
      position: sticky;
      top: 76px;
    }

    .detail-category {
      font-size: 12px;
      font-weight: 600;
      color: var(--color-primary-text-sm);
      text-transform: uppercase;
      letter-spacing: 1px;
      margin-bottom: var(--sp-md);
      font-family: var(--font-en);
    }

    .detail-info h1 {
      font-size: 42px;
      font-weight: 800;
      line-height: 1.1;
      letter-spacing: -2px;
      margin-bottom: var(--sp-md);
    }

    .detail-author {
      font-size: 17px;
      color: var(--color-text-secondary);
      margin-bottom: var(--sp-2xl);
    }

    .detail-rating {
      display: flex;
      align-items: center;
      gap: var(--sp-sm);
      font-size: 14px;
      color: var(--color-text-secondary);
      margin-bottom: var(--sp-3xl);
    }

    .detail-rating .star { color: #FF9500; }

    .detail-desc {
      font-size: 16px;
      line-height: 1.75;
      color: var(--color-text-secondary);
      margin-bottom: var(--sp-4xl);
      white-space: pre-line;
      letter-spacing: -0.2px;
    }

    .detail-price-section {
      padding: var(--sp-3xl);
      background: rgba(0,0,0,0.02);
      border-radius: var(--radius-lg);
      margin-bottom: var(--sp-xl);
    }

    .detail-price {
      font-family: var(--font-en);
      font-size: 44px;
      font-weight: 800;
      letter-spacing: -2px;
      margin-bottom: var(--sp-xs);
    }

    .detail-price .unit {
      font-family: var(--font-kr);
      font-size: 20px;
      font-weight: 600;
    }

    .detail-price .original {
      font-size: 18px;
      color: var(--color-text-tertiary);
      text-decoration: line-through;
      font-weight: 400;
      margin-left: var(--sp-md);
    }

    .detail-price-note {
      font-size: 13px;
      color: var(--color-text-tertiary);
      letter-spacing: -0.1px;
    }

    .btn-purchase {
      width: 100%;
      padding: var(--sp-xl) var(--sp-2xl);
      font-size: 17px;
      font-weight: 600;
      color: #fff;
      background: var(--color-primary);
      border-radius: var(--radius-pill);
      transition: transform 0.25s cubic-bezier(0.16, 1, 0.3, 1),
                  background 0.2s ease,
                  box-shadow 0.25s cubic-bezier(0.16, 1, 0.3, 1);
      letter-spacing: -0.2px;
      will-change: transform;
    }

    .btn-purchase:hover {
      background: var(--color-primary-hover);
      transform: scale(1.015);
      box-shadow: 0 6px 20px rgba(206,0,0,0.3);
    }

    .btn-purchase:active {
      transform: scale(0.97);
      transition-duration: 0.1s;
    }

    .btn-purchase:disabled {
      background: var(--color-text-tertiary);
      cursor: not-allowed;
      box-shadow: none;
      transform: none;
    }

    .btn-purchase.purchased {
      background: var(--color-success);
    }

    .btn-purchase.purchased:hover {
      box-shadow: 0 6px 20px rgba(36,138,61,0.3);
    }

    .detail-meta {
      margin-top: var(--sp-3xl);
    }

    .detail-meta-row {
      display: flex;
      justify-content: space-between;
      font-size: 14px;
      padding: var(--sp-md) 0;
    }

    .detail-meta-row .label {
      color: var(--color-text-tertiary);
    }

    .detail-meta-row .value {
      font-weight: 500;
      color: var(--color-text);
    }

    /* ========== My Page ========== */
    .my-header {
      padding: var(--sp-6xl) 0 var(--sp-3xl);
    }

    .my-header h2 {
      font-size: 32px;
      font-weight: 800;
      letter-spacing: -1px;
    }

    .my-header p {
      font-size: 16px;
      color: var(--color-text-secondary);
      margin-top: var(--sp-sm);
    }

    .my-tabs {
      display: flex;
      gap: var(--sp-xs);
      margin-bottom: var(--sp-3xl);
    }

    .my-tab {
      padding: var(--sp-sm) var(--sp-xl);
      font-size: 14px;
      font-weight: 500;
      color: var(--color-text-secondary);
      border-radius: var(--radius-pill);
      transition: all 0.2s;
    }

    .my-tab:hover { color: var(--color-text); }

    .my-tab.active {
      background: var(--color-text);
      color: #fff;
      font-weight: 600;
    }

    .purchase-list {
      display: flex;
      flex-direction: column;
      gap: var(--sp-md);
      padding-bottom: var(--sp-8xl);
    }

    .purchase-item {
      display: flex;
      align-items: center;
      gap: var(--sp-xl);
      padding: var(--sp-xl);
      background: var(--color-surface);
      border-radius: var(--radius-lg);
      transition: background 0.3s cubic-bezier(0.23,1,0.32,1),
                  transform 0.3s cubic-bezier(0.23,1,0.32,1);
    }

    .purchase-item:hover {
      background: rgba(0,0,0,0.01);
    }

    .purchase-item-cover {
      width: 72px;
      height: 54px;
      border-radius: var(--radius-sm);
      background: #f2f2f5;
      overflow: hidden;
      flex-shrink: 0;
    }

    .purchase-item-cover img {
      width: 100%;
      height: 100%;
      object-fit: cover;
    }

    .purchase-item-info {
      flex: 1;
      min-width: 0;
    }

    .purchase-item-title {
      font-size: 15px;
      font-weight: 600;
      margin-bottom: var(--sp-xs);
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap;
      letter-spacing: -0.3px;
    }

    .purchase-item-date {
      font-size: 13px;
      color: var(--color-text-tertiary);
    }

    .btn-download {
      padding: var(--sp-sm) var(--sp-xl);
      font-size: 13px;
      font-weight: 600;
      color: var(--color-primary-text-sm);
      background: var(--color-primary-bg);
      border-radius: var(--radius-pill);
      flex-shrink: 0;
      transition: background 0.2s;
      letter-spacing: -0.1px;
    }

    .btn-download:hover {
      background: rgba(206,0,0,0.12);
    }

    /* ========== Login Modal ========== */
    .modal-overlay {
      position: fixed;
      inset: 0;
      z-index: 200;
      background: rgba(0,0,0,0.35);
      backdrop-filter: blur(24px) saturate(180%);
      -webkit-backdrop-filter: blur(24px) saturate(180%);
      display: flex;
      align-items: center;
      justify-content: center;
      opacity: 0;
      visibility: hidden;
      transition: opacity 0.25s ease, visibility 0.25s;
    }

    .modal-overlay.active {
      opacity: 1;
      visibility: visible;
    }

    .modal {
      background: var(--color-surface);
      border-radius: var(--radius-xl);
      padding: var(--sp-5xl);
      width: 90%;
      max-width: 380px;
      box-shadow: var(--shadow-elevated);
      text-align: center;
      position: relative;
      transform: scale(0.95) translateY(8px);
      opacity: 0;
      transition: transform 0.2s ease-in,
                  opacity 0.15s ease-in;
    }

    .modal-overlay.active .modal {
      transform: scale(1) translateY(0);
      opacity: 1;
      transition: transform 0.4s cubic-bezier(0.34, 1.56, 0.64, 1),
                  opacity 0.25s ease-out;
    }

    .modal-close {
      position: absolute;
      top: var(--sp-lg);
      right: var(--sp-lg);
      width: 44px;
      height: 44px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 16px;
      color: var(--color-text-tertiary);
      border-radius: 50%;
      transition: background 0.2s, color 0.2s;
    }

    .modal-close:hover {
      background: rgba(0,0,0,0.06);
      color: var(--color-text);
    }

    .modal h2 {
      font-size: 24px;
      font-weight: 800;
      letter-spacing: -0.8px;
      margin-bottom: var(--sp-sm);
    }

    .modal p {
      font-size: 15px;
      color: var(--color-text-secondary);
      margin-bottom: var(--sp-3xl);
      line-height: 1.5;
    }

    .btn-google {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: var(--sp-md);
      width: 100%;
      padding: var(--sp-lg) var(--sp-xl);
      font-size: 15px;
      font-weight: 600;
      color: var(--color-text);
      background: var(--color-surface);
      border: 1px solid var(--color-border-strong);
      border-radius: var(--radius-pill);
      transition: transform 0.2s cubic-bezier(0.16, 1, 0.3, 1),
                  background 0.2s ease,
                  border-color 0.2s ease,
                  box-shadow 0.2s ease;
    }

    .btn-google:hover {
      background: var(--color-bg);
      border-color: rgba(0,0,0,0.18);
      box-shadow: 0 2px 12px rgba(0,0,0,0.06);
    }

    .btn-google:active {
      transform: scale(0.97);
      transition-duration: 0.1s;
    }

    .btn-google svg {
      width: 18px;
      height: 18px;
    }

    .modal-note {
      margin-top: var(--sp-xl);
      font-size: 12px;
      color: var(--color-text-tertiary);
    }

    /* ========== Toast ========== */
    .toast-container {
      position: fixed;
      top: var(--sp-6xl);
      left: 50%;
      transform: translateX(-50%);
      z-index: 300;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: var(--sp-sm);
    }

    .toast {
      padding: var(--sp-md) var(--sp-2xl);
      background: rgba(29,29,31,0.9);
      color: #fff;
      font-size: 14px;
      font-weight: 500;
      border-radius: var(--radius-pill);
      box-shadow: var(--shadow-elevated);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      animation: toastIn 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
      letter-spacing: -0.2px;
      transition: opacity 0.25s ease-in, transform 0.25s ease-in;
    }

    .toast.error {
      background: #ff3b30;
    }

    .toast.success {
      background: var(--color-success);
    }

    @keyframes toastIn {
      from { opacity: 0; transform: translateY(-16px) scale(0.9); }
      to { opacity: 1; transform: translateY(0) scale(1); }
    }

    /* ========== Loading ========== */
    .spinner {
      display: inline-block;
      width: 20px;
      height: 20px;
      border: 2px solid rgba(255,255,255,0.3);
      border-top-color: #fff;
      border-radius: 50%;
      animation: spin 0.6s linear infinite;
    }

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

    .page-loading {
      text-align: center;
      padding: var(--sp-7xl) 0;
    }

    .page-loading .spinner {
      width: 28px;
      height: 28px;
      border-color: rgba(0,0,0,0.08);
      border-top-color: var(--color-primary);
    }

    /* ========== Skeleton Loading (Apple-style shimmer) ========== */
    @keyframes shimmer {
      0% { background-position: 200% 0; }
      100% { background-position: -200% 0; }
    }

    .skeleton-card {
      background: var(--color-surface);
      border-radius: var(--radius-xl);
      overflow: hidden;
    }

    .skeleton-cover {
      aspect-ratio: 3/4;
      background: linear-gradient(90deg, #f0f0f3 25%, #f5f5f7 50%, #f0f0f3 75%);
      background-size: 200% 100%;
      animation: shimmer 1.8s ease-in-out infinite;
    }

    .skeleton-body {
      padding: var(--sp-xl);
    }

    .skeleton-line {
      height: 12px;
      margin-bottom: var(--sp-sm);
      background: linear-gradient(90deg, #f0f0f3 25%, #f5f5f7 50%, #f0f0f3 75%);
      background-size: 200% 100%;
      animation: shimmer 1.8s ease-in-out infinite;
      border-radius: 6px;
    }

    .skeleton-line.w-40 { width: 40%; }
    .skeleton-line.w-60 { width: 60%; }
    .skeleton-line.w-80 { width: 80%; }
    .skeleton-line.h-lg { height: 18px; }
    .skeleton-line.h-xl { height: 24px; }

    .skeleton-detail-layout {
      display: grid;
      grid-template-columns: 380px 1fr;
      gap: var(--sp-6xl);
      padding: var(--sp-4xl) 0 var(--sp-9xl);
      align-items: start;
    }

    .skeleton-detail-cover {
      aspect-ratio: 3/4;
      border-radius: var(--radius-xl);
      background: linear-gradient(90deg, #f0f0f3 25%, #f5f5f7 50%, #f0f0f3 75%);
      background-size: 200% 100%;
      animation: shimmer 1.8s ease-in-out infinite;
    }

    .skeleton-purchase-item {
      display: flex;
      align-items: center;
      gap: var(--sp-xl);
      padding: var(--sp-xl);
      background: var(--color-surface);
      border-radius: var(--radius-lg);
    }

    .skeleton-purchase-cover {
      width: 72px;
      height: 54px;
      border-radius: var(--radius-sm);
      background: linear-gradient(90deg, #f0f0f3 25%, #f5f5f7 50%, #f0f0f3 75%);
      background-size: 200% 100%;
      animation: shimmer 1.8s ease-in-out infinite;
      flex-shrink: 0;
    }

    @media (max-width: 768px) {
      .skeleton-detail-layout {
        grid-template-columns: 1fr;
        gap: var(--sp-3xl);
      }
      .skeleton-detail-cover {
        max-width: 320px;
        margin: 0 auto;
      }
    }

    /* ========== Focus Ring (accessibility) ========== */
    :focus-visible {
      outline: 3px solid rgba(206,0,0,0.4);
      outline-offset: 2px;
      border-radius: var(--radius-sm);
    }

    button:focus-visible {
      outline: 3px solid rgba(206,0,0,0.4);
      outline-offset: 2px;
    }

    /* ========== Reduced Motion ========== */
    @media (prefers-reduced-motion: reduce) {
      *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
      }
      .fade-in { opacity: 1; transform: none; }
      .hero { transform: none !important; opacity: 1 !important; }
      .modal { transform: none !important; opacity: 1 !important; }
      .modal-overlay.active .modal { transform: none !important; }
    }

    /* ========== Footer ========== */
    .footer {
      padding: var(--sp-4xl) 0 var(--sp-3xl);
      margin-top: var(--sp-3xl);
    }

    .footer-inner {
      display: flex;
      justify-content: space-between;
      align-items: center;
    }

    .footer-logo {
      font-family: var(--font-en);
      font-size: 13px;
      font-weight: 700;
      color: var(--color-text-tertiary);
      letter-spacing: -0.3px;
    }

    .footer-text {
      font-size: 11px;
      color: var(--color-text-tertiary);
    }

    .footer-links {
      display: flex;
      gap: var(--sp-lg);
    }

    .footer-links a {
      font-size: 11px;
      color: var(--color-text-tertiary);
      transition: color 0.2s;
    }

    .footer-links a:hover {
      color: var(--color-text-secondary);
    }

    /* ========== Table of Contents (collapsible) ========== */
    .detail-toc {
      margin-top: var(--sp-4xl);
      padding-top: var(--sp-3xl);
    }

    .detail-toc-toggle {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
      padding: 0;
      font-size: 18px;
      font-weight: 700;
      letter-spacing: -0.4px;
      color: var(--color-text);
      cursor: pointer;
      text-align: left;
    }

    .detail-toc-toggle svg {
      width: 20px;
      height: 20px;
      color: var(--color-text-tertiary);
      transition: transform 0.3s cubic-bezier(0.23, 1, 0.32, 1);
    }

    .detail-toc-toggle.open svg {
      transform: rotate(180deg);
    }

    .detail-toc-content {
      font-size: 15px;
      line-height: 1.8;
      color: var(--color-text-secondary);
      white-space: pre-line;
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s cubic-bezier(0.23, 1, 0.32, 1),
                  margin 0.3s;
      margin-top: 0;
    }

    .detail-toc-content.open {
      max-height: 2000px;
      margin-top: var(--sp-xl);
    }

    /* ========== Mobile Menu ========== */
    .mobile-menu-btn {
      display: none;
      width: 44px;
      height: 44px;
      align-items: center;
      justify-content: center;
      border-radius: var(--radius-pill);
      transition: background 0.2s;
      flex-shrink: 0;
    }

    .mobile-menu-btn:hover {
      background: rgba(0,0,0,0.04);
    }

    .mobile-menu-btn svg {
      width: 20px;
      height: 20px;
      color: var(--color-text);
    }

    .mobile-nav-overlay {
      position: fixed;
      inset: 0;
      z-index: 150;
      background: rgba(0,0,0,0.3);
      backdrop-filter: blur(8px);
      -webkit-backdrop-filter: blur(8px);
      opacity: 0;
      visibility: hidden;
      transition: opacity 0.25s ease, visibility 0.25s;
    }

    .mobile-nav-overlay.active {
      opacity: 1;
      visibility: visible;
    }

    .mobile-nav-drawer {
      position: fixed;
      top: 0;
      right: 0;
      z-index: 151;
      width: 280px;
      max-width: 85vw;
      height: 100vh;
      background: var(--color-surface);
      box-shadow: var(--shadow-elevated);
      transform: translateX(100%);
      transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
      display: flex;
      flex-direction: column;
      padding: var(--sp-2xl);
    }

    .mobile-nav-drawer.active {
      transform: translateX(0);
    }

    .mobile-nav-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin-bottom: var(--sp-3xl);
    }

    .mobile-nav-header .logo {
      font-size: 16px;
    }

    .mobile-nav-close {
      width: 44px;
      height: 44px;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 50%;
      color: var(--color-text-tertiary);
      transition: background 0.2s, color 0.2s;
    }

    .mobile-nav-close:hover {
      background: rgba(0,0,0,0.06);
      color: var(--color-text);
    }

    .mobile-nav-links {
      display: flex;
      flex-direction: column;
      gap: var(--sp-xs);
    }

    .mobile-nav-link {
      padding: var(--sp-md) var(--sp-lg);
      font-size: 16px;
      font-weight: 500;
      color: var(--color-text);
      border-radius: var(--radius-pill);
      transition: background 0.2s;
      text-align: left;
    }

    .mobile-nav-link:hover {
      background: rgba(0,0,0,0.04);
    }

    .mobile-nav-link.cta {
      color: var(--color-primary);
      font-weight: 600;
    }

    .mobile-nav-user {
      display: flex;
      align-items: center;
      gap: var(--sp-md);
      padding: var(--sp-lg);
      margin-top: auto;
    }

    .mobile-nav-user .nav-avatar {
      width: 36px;
      height: 36px;
    }

    .mobile-nav-user-info {
      font-size: 14px;
      font-weight: 500;
      color: var(--color-text);
    }

    .mobile-nav-search {
      position: relative;
      margin-bottom: var(--sp-xl);
    }

    .mobile-nav-search input {
      width: 100%;
      height: 40px;
      padding: 0 var(--sp-lg) 0 36px;
      border: none;
      border-radius: var(--radius-pill);
      font-size: 14px;
      font-family: var(--font);
      background: rgba(0,0,0,0.04);
      color: var(--color-text);
      outline: none;
      transition: background 0.2s, box-shadow 0.3s;
    }

    .mobile-nav-search input::placeholder {
      color: var(--color-text-tertiary);
    }

    .mobile-nav-search input:focus {
      background: rgba(0,0,0,0.06);
      box-shadow: 0 0 0 3px rgba(206,0,0,0.12);
    }

    .mobile-nav-search .search-icon {
      position: absolute;
      left: var(--sp-md);
      top: 50%;
      transform: translateY(-50%);
      width: 14px;
      height: 14px;
      color: var(--color-text-tertiary);
    }

    .mobile-nav-search .search-icon svg {
      width: 100%;
      height: 100%;
    }

    /* ========== Scroll to Top ========== */
    .scroll-top-btn {
      position: fixed;
      bottom: var(--sp-3xl);
      right: var(--sp-3xl);
      width: 40px;
      height: 40px;
      border-radius: 50%;
      background: rgba(255,255,255,0.85);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      color: var(--color-text);
      box-shadow: 0 2px 12px rgba(0,0,0,0.08), 0 0 0 0.5px rgba(0,0,0,0.06);
      display: flex;
      align-items: center;
      justify-content: center;
      z-index: 90;
      opacity: 0;
      transform: translateY(12px);
      pointer-events: none;
      transition: opacity 0.3s cubic-bezier(0.23,1,0.32,1),
                  transform 0.3s cubic-bezier(0.23,1,0.32,1),
                  background 0.2s;
    }

    .scroll-top-btn.visible {
      opacity: 1;
      transform: translateY(0);
      pointer-events: auto;
    }

    .scroll-top-btn:hover {
      background: var(--color-bg);
      box-shadow: 0 6px 20px rgba(0,0,0,0.12), 0 0 1px rgba(0,0,0,0.1);
      transform: translateY(-2px);
    }

    .scroll-top-btn:active {
      transform: scale(0.95);
      transition-duration: 0.1s;
    }

    .scroll-top-btn svg {
      width: 18px;
      height: 18px;
    }

    /* ========== Responsive ========== */
    @media (max-width: 960px) {
      .book-grid { grid-template-columns: repeat(2, 1fr); }
      .hero h1 { font-size: 52px; letter-spacing: -2.5px; }
      .hero { padding: var(--sp-8xl) 0 var(--sp-6xl); }
      .detail-layout {
        grid-template-columns: 320px 1fr;
        gap: var(--sp-4xl);
      }
    }

    @media (max-width: 768px) {
      :root { --page-pad: 20px; }

      .book-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--sp-md);
      }

      .detail-layout {
        grid-template-columns: 1fr;
        gap: var(--sp-3xl);
      }

      .detail-cover {
        max-width: 320px;
        margin: 0 auto;
      }

      .detail-info { position: static; }

      .hero h1 {
        font-size: 38px;
        letter-spacing: -1.8px;
      }

      .hero p { font-size: 17px; }
      .hero { padding: var(--sp-7xl) 0 var(--sp-5xl); }

      .header-search { display: none; }
      .header-nav { display: none; }
      .mobile-menu-btn { display: flex; }

      .category-bar {
        width: fit-content;
        max-width: 100%;
        overflow-x: auto;
      }

      .footer-inner {
        flex-direction: column;
        gap: var(--sp-md);
        text-align: center;
      }

      .footer-links { justify-content: center; }
    }

    @media (max-width: 640px) {
      .hero h1 { font-size: 34px; letter-spacing: -1.5px; }
      .hero { padding: var(--sp-6xl) 0 var(--sp-4xl); }
      .hero-cta { font-size: 14px; padding: var(--sp-md) var(--sp-2xl); }

      .book-card-body {
        padding: var(--sp-lg);
      }

      .book-card-title { font-size: 14px; }
      .book-card-price { font-size: 15px; }
      .book-card-author { font-size: 12px; }
      .book-card-cta { display: none; }

      .detail-info h1 { font-size: 28px; letter-spacing: -1px; }
      .detail-price { font-size: 32px; }

      .purchase-item {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--sp-md);
      }

      .btn-download { width: 100%; text-align: center; }

      .my-header h2 { font-size: 26px; }
    }

    @media (max-width: 375px) {
      :root { --page-pad: 16px; }
      .book-grid { grid-template-columns: 1fr; }
      .hero h1 { font-size: 26px; letter-spacing: -1px; }
      .hero p { font-size: 15px; }
      .hero { padding: var(--sp-5xl) 0 var(--sp-3xl); }
      .book-card-body { padding: var(--sp-md); }
      .book-card-title { font-size: 14px; }
      .book-card-price { font-size: 14px; }
      .detail-info h1 { font-size: 24px; letter-spacing: -0.8px; }
      .detail-price { font-size: 28px; letter-spacing: -1px; }
      .detail-price-section { padding: var(--sp-2xl); }
      .modal { padding: var(--sp-3xl); }
      .modal h2 { font-size: 20px; }
      .my-header h2 { font-size: 22px; }
      .category-tag { font-size: 12px; padding: var(--sp-sm) var(--sp-lg); }
    }

    /* ========== CSP 대응: 인라인 style 대체 클래스 ========== */
    .login-modal-logo {
      font-family: var(--font-en);
      font-size: 22px;
      font-weight: 800;
      letter-spacing: -0.6px;
      margin-bottom: var(--sp-2xl);
    }

    .login-modal-logo .accent,
    .footer-logo .accent {
      color: var(--color-primary);
    }