:root {
      --font-sans: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      --bg-main: #f1f5f9;
      --bg-card: #ffffff;
      --bg-subtle: #e2e8f0;
      --border-color: #e2e8f0;
      --border-hover: #cbd5e1;
      --text-main: #0f172a;
      --text-muted: #475569;
      --text-dim: #94a3b8;
      
      --primary: #2563eb;
      --primary-hover: #1d4ed8;
      --primary-light: #eff6ff;
      --primary-border: #bfdbfe;
      
      --accent-green: #059669;
      --accent-green-bg: #ecfdf5;
      --accent-green-border: #a7f3d0;
      
      --accent-amber: #d97706;
      --accent-amber-bg: #fffbeb;
      --accent-amber-border: #fde68a;

      --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
      --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
      --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
      --shadow-hover: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.04);

      --radius-sm: 8px;
      --radius-md: 12px;
      --radius-lg: 16px;
      --radius-xl: 20px;
      --radius-pill: 9999px;
    }

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

    body {
      font-family: var(--font-sans);
      background-color: var(--bg-main);
      color: var(--text-main);
      min-height: 100vh;
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
      display: flex;
      flex-direction: column;
    }

    a {
      color: inherit;
      text-decoration: none;
    }

    button {
      font-family: inherit;
      border: none;
      background: none;
      cursor: pointer;
    }

    .container {
      width: 100%;
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 20px;
    }
    @media (min-width: 1440px) {
      .container {
        max-width: 1440px;
        padding: 0 24px;
      }
    }
    @media (min-width: 1536px) {
      .container {
        max-width: 1536px;
        padding: 0 32px;
      }
    }

    /* Hub Hero (Split Wide Layout) */
    .hub-hero {
      padding: 36px 0 24px;
      display: grid;
      grid-template-columns: 1.15fr 0.85fr;
      gap: 36px;
      align-items: center;
      width: 100%;
    }

    .hub-hero-col-info {
      display: flex;
      flex-direction: column;
      align-items: flex-start;
      text-align: left;
    }

    .hub-hero-badge {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      font-size: 0.76rem;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.06em;
      color: var(--primary);
      background: var(--primary-light);
      border: 1px solid var(--primary-border);
      padding: 4px 12px;
      border-radius: var(--radius-pill);
      margin-bottom: 12px;
    }

    .hub-title {
      font-size: 2.5rem;
      font-weight: 800;
      color: var(--text-main);
      letter-spacing: -0.03em;
      margin-bottom: 10px;
      line-height: 1.15;
    }

    .hub-subtitle {
      font-size: 1.05rem;
      color: var(--text-muted);
      line-height: 1.6;
      margin-bottom: 16px;
      max-width: none;
    }

    .hub-hero-pills {
      display: flex;
      align-items: center;
      gap: 8px;
      flex-wrap: wrap;
    }

    .hub-hero-pill {
      font-size: 0.80rem;
      font-weight: 600;
      color: var(--text-muted);
      background: var(--bg-card);
      border: 1px solid var(--border-color);
      padding: 5px 12px;
      border-radius: var(--radius-pill);
      display: inline-flex;
      align-items: center;
      gap: 6px;
      box-shadow: 0 1px 2px rgba(0, 0, 0, 0.03);
    }

    /* Hero Level Switcher Card */
    .hub-hero-col-action {
      display: flex;
      flex-direction: column;
      width: 100%;
    }

    .hub-level-card {
      background: var(--bg-card);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-xl);
      padding: 22px 24px;
      box-shadow: var(--shadow-sm);
      display: flex;
      flex-direction: column;
      gap: 12px;
      width: 100%;
      box-sizing: border-box;
    }

    .hub-level-prompt {
      font-size: 0.78rem;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.06em;
      color: var(--text-dim);
      display: flex;
      align-items: center;
      gap: 6px;
    }

    .hub-level-tabs {
      display: flex;
      flex-direction: column;
      gap: 8px;
      width: 100%;
    }

    .hub-level-btn {
      display: flex;
      align-items: center;
      gap: 12px;
      padding: 10px 14px;
      border-radius: var(--radius-lg);
      background: var(--bg-subtle);
      border: 2px solid transparent;
      cursor: pointer;
      transition: all 0.22s ease;
      text-align: left;
      user-select: none;
    }

    .hub-level-btn:hover {
      background: #e2e8f0;
      border-color: var(--border-hover);
    }

    .hub-level-btn.active#hub-level-btn-a1 {
      background: #ecfdf5;
      border-color: #10b981;
      box-shadow: 0 4px 14px rgba(16, 185, 129, 0.15);
    }

    .hub-level-btn.active#hub-level-btn-a1 .hub-level-name {
      color: #065f46;
      font-weight: 800;
    }

    .hub-level-btn.active#hub-level-btn-a1 .hub-level-sub {
      color: #047857;
      font-weight: 600;
    }

    .hub-level-btn.active#hub-level-btn-a2 {
      background: #f0fdfa;
      border-color: #0d9488;
      box-shadow: 0 4px 14px rgba(13, 148, 136, 0.15);
    }

    .hub-level-btn.active#hub-level-btn-a2 .hub-level-name {
      color: #115e59;
      font-weight: 800;
    }

    .hub-level-btn.active#hub-level-btn-a2 .hub-level-sub {
      color: #0f766e;
      font-weight: 600;
    }

    .hub-level-btn.active#hub-level-btn-b1 {
      background: #eef2ff;
      border-color: #4f46e5;
      box-shadow: 0 4px 14px rgba(79, 70, 229, 0.15);
    }

    .hub-level-btn.active#hub-level-btn-b1 .hub-level-name {
      color: #3730a3;
      font-weight: 800;
    }

    .hub-level-btn.active#hub-level-btn-b1 .hub-level-sub {
      color: #4338ca;
      font-weight: 600;
    }

    .hub-level-icon {
      font-size: 1.55rem;
      line-height: 1;
      flex-shrink: 0;
    }

    .hub-level-text {
      display: flex;
      flex-direction: column;
      min-width: 0;
    }

    .hub-level-name {
      font-size: 0.94rem;
      font-weight: 700;
      color: var(--text-main);
      line-height: 1.25;
      transition: color 0.2s ease;
    }

    .hub-level-sub {
      font-size: 0.76rem;
      font-weight: 500;
      color: var(--text-muted);
      margin-top: 2px;
      line-height: 1.2;
      transition: color 0.2s ease;
    }

    .hub-level-hint {
      font-size: 0.84rem;
      color: var(--text-muted);
      line-height: 1.45;
      display: flex;
      align-items: flex-start;
      gap: 6px;
      padding: 0;
    }

    .hub-level-hint strong {
      color: var(--text-main);
    }

    .hub-hint-icon {
      flex-shrink: 0;
      margin-top: 1px;
    }

    /* Hub Controls (Categories & Sort) */
    .hub-controls {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 16px;
      flex-wrap: wrap;
      margin: 20px 0 28px;
      padding: 14px 18px;
      background: var(--bg-card);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-sm);
    }

    .category-filters {
      display: flex;
      align-items: center;
      gap: 8px;
      flex-wrap: wrap;
    }

    .category-pill {
      font-size: 0.84rem;
      font-weight: 600;
      padding: 6px 14px;
      border-radius: var(--radius-pill);
      border: 1px solid var(--border-color);
      background: var(--bg-subtle);
      color: var(--text-muted);
      cursor: pointer;
      transition: all 0.2s ease;
      display: inline-flex;
      align-items: center;
      gap: 6px;
    }

    .category-pill:hover {
      border-color: var(--primary-border);
      color: var(--primary);
      background: var(--primary-light);
    }

    .category-pill.active {
      background: var(--primary);
      color: #ffffff;
      border-color: var(--primary);
      font-weight: 700;
      box-shadow: 0 2px 6px rgba(37, 99, 235, 0.25);
    }

    .category-count {
      font-size: 0.75rem;
      padding: 1px 6px;
      border-radius: var(--radius-pill);
      background: rgba(0, 0, 0, 0.08);
    }

    .category-pill.active .category-count {
      background: rgba(255, 255, 255, 0.25);
      color: #ffffff;
    }

    .sort-box {
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .sort-label {
      font-size: 0.84rem;
      font-weight: 600;
      color: var(--text-muted);
      white-space: nowrap;
    }

    .sort-select {
      font-size: 0.84rem;
      font-family: inherit;
      font-weight: 600;
      color: var(--text-main);
      background: var(--bg-main);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-sm);
      padding: 6px 12px;
      cursor: pointer;
      outline: none;
      transition: border-color 0.2s ease;
    }

    .sort-select:focus {
      border-color: var(--primary);
    }

    /* Articles Grid */
    .articles-grid {
      display: grid;
      grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
      gap: 28px;
      padding: 20px 0 60px;
    }

    .article-card {
      background: var(--bg-card);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-xl);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
      display: flex;
      flex-direction: column;
      cursor: pointer;
    }

    .article-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
      border-color: var(--border-hover);
    }

    .card-banner {
      height: 200px;
      overflow: hidden;
      position: relative;
      background: var(--bg-subtle);
    }

    .card-image {
      width: 100%;
      height: 100%;
      object-fit: cover;
      display: block;
      transition: transform 0.4s ease;
    }

    .article-card:hover .card-image {
      transform: scale(1.05);
    }

    .card-body {
      padding: 24px;
      display: flex;
      flex-direction: column;
      flex-grow: 1;
    }

    .card-meta-row {
      display: flex;
      align-items: center;
      gap: 10px;
      margin-bottom: 12px;
      flex-wrap: wrap;
    }

    .badge-level {
      font-size: 0.75rem;
      font-weight: 700;
      padding: 3px 10px;
      border-radius: var(--radius-pill);
      background: #ecfdf5;
      color: #059669;
      border: 1px solid #a7f3d0;
      display: inline-flex;
      align-items: center;
      gap: 4px;
    }

    .badge-level.badge-level-a2 {
      background: #f0fdfa;
      color: #0d9488;
      border: 1px solid #99f6e4;
    }

    .badge-level.badge-level-b1 {
      background: #eef2ff;
      color: #4338ca;
      border: 1px solid #c7d2fe;
    }

    .badge-dual-note {
      font-size: 0.72rem;
      font-weight: 500;
      color: var(--text-dim);
    }

    .badge-time {
      font-size: 0.75rem;
      font-weight: 600;
      color: var(--text-dim);
      display: flex;
      align-items: center;
      gap: 4px;
    }

    .card-title {
      font-size: 1.35rem;
      font-weight: 700;
      color: var(--text-main);
      margin-bottom: 10px;
      line-height: 1.3;
      letter-spacing: -0.01em;
    }

    .card-excerpt {
      font-size: 0.95rem;
      color: var(--text-muted);
      line-height: 1.55;
      margin-bottom: 20px;
      flex-grow: 1;
    }

    .card-footer {
      display: flex;
      align-items: center;
      justify-content: space-between;
      border-top: 1px solid var(--border-color);
      padding-top: 16px;
      margin-top: auto;
      gap: 12px;
    }

    .card-category-badge {
      position: absolute;
      top: 14px;
      left: 14px;
      z-index: 2;
      font-size: 0.78rem;
      font-weight: 700;
      color: #0f172a;
      background: rgba(255, 255, 255, 0.94);
      backdrop-filter: blur(8px);
      -webkit-backdrop-filter: blur(8px);
      border: 1px solid rgba(255, 255, 255, 0.75);
      padding: 5px 12px;
      border-radius: var(--radius-pill);
      box-shadow: 0 4px 12px rgba(15, 23, 42, 0.12);
      transition: all 0.2s ease;
      display: inline-flex;
      align-items: center;
      gap: 5px;
      cursor: pointer;
      max-width: calc(100% - 28px);
      white-space: nowrap;
      overflow: hidden;
      text-overflow: ellipsis;
    }

    .card-category-badge:hover {
      background: var(--primary);
      color: #ffffff;
      border-color: var(--primary);
      transform: translateY(-2px);
      box-shadow: 0 6px 16px rgba(37, 99, 235, 0.35);
    }

    .card-category {
      font-size: 0.78rem;
      font-weight: 700;
      color: var(--primary);
      background: var(--primary-light);
      border: 1px solid var(--primary-border);
      padding: 3px 10px;
      border-radius: var(--radius-pill);
      transition: all 0.2s ease;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      cursor: pointer;
    }

    .card-category:hover {
      background: var(--primary);
      color: #ffffff;
      border-color: var(--primary);
      transform: translateY(-1px);
    }

    .card-btn {
      font-size: 0.9rem;
      font-weight: 700;
      color: var(--primary);
      display: inline-flex;
      align-items: center;
      gap: 6px;
      white-space: nowrap;
      flex-shrink: 0;
      margin-left: auto;
      transition: gap 0.2s ease;
      text-decoration: none;
    }

    .article-card:hover .card-btn {
      gap: 10px;
      color: var(--primary-hover);
    }

    /* -------------------------------------------------------------
       SINGLE ARTICLE VIEW
    ------------------------------------------------------------- */
    .single-article-view {
      padding: 36px 0 80px;
      width: 100%;
      max-width: 100%;
      margin: 0 auto;
    }


    .article-header {
      background: var(--bg-card);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-xl);
      padding: 32px 36px;
      box-shadow: var(--shadow-sm);
      margin-bottom: 24px;
    }

    .article-header-meta {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-bottom: 12px;
      flex-wrap: wrap;
    }

    .art-level-note {
      font-size: 0.82rem;
      font-weight: 600;
      color: var(--text-muted);
      background: var(--bg-subtle);
      border: 1px solid var(--border-color);
      padding: 4px 12px;
      border-radius: var(--radius-pill);
      display: inline-flex;
      align-items: center;
      gap: 6px;
    }

    .article-main-title {
      font-size: 2.2rem;
      font-weight: 800;
      color: var(--text-main);
      line-height: 1.25;
      letter-spacing: -0.02em;
      margin-bottom: 14px;
    }

    .article-header-desc {
      font-size: 1.05rem;
      color: var(--text-muted);
      line-height: 1.6;
    }

    /* Article Hero Image */
    .article-hero-wrap {
      border-radius: var(--radius-xl);
      overflow: hidden;
      margin-bottom: 28px;
      box-shadow: var(--shadow-sm);
      border: 1px solid var(--border-color);
      max-height: 520px;
      background: var(--bg-subtle);
    }

    .article-hero-img {
      width: 100%;
      height: 100%;
      max-height: 520px;
      object-fit: cover;
      display: block;
    }

    /* Reading Text Box */
    .reading-box {
      background: var(--bg-card);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-xl);
      padding: 36px;
      box-shadow: var(--shadow-sm);
      margin-bottom: 36px;
    }

    .reading-box-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding-bottom: 16px;
      margin-bottom: 24px;
      border-bottom: 1px solid var(--border-color);
    }

    .reading-box-title {
      font-size: 1.1rem;
      font-weight: 700;
      color: var(--text-main);
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .reading-tip {
      font-size: 0.85rem;
      color: var(--text-muted);
      background: var(--bg-subtle);
      padding: 6px 12px;
      border-radius: var(--radius-md);
      display: flex;
      align-items: center;
      gap: 6px;
    }

    .reading-content p {
      font-size: 1.15rem;
      line-height: 1.85;
      color: #1e293b;
      margin-bottom: 20px;
    }

    .reading-content p:last-child {
      margin-bottom: 0;
    }

    /* Bold Clickable Target Words */
    .vocab-ref {
      display: inline-block;
      font-weight: 800;
      color: var(--primary);
      background: var(--primary-light);
      padding: 1px 6px;
      border-radius: 6px;
      border: 1px solid var(--primary-border);
      cursor: pointer;
      transition: all 0.15s ease;
      text-decoration: none;
      vertical-align: baseline;
    }

    .vocab-ref:hover {
      background: #dbeafe;
      border-color: #93c5fd;
      transform: translateY(-1px);
    }

    /* -------------------------------------------------------------
       SECTION: GLOSSARY & AUDIO
    ------------------------------------------------------------- */
    .section-block {
      margin-bottom: 40px;
    }

    .section-heading {
      font-size: 1.45rem;
      font-weight: 800;
      color: var(--text-main);
      margin-bottom: 8px;
      letter-spacing: -0.02em;
      display: flex;
      align-items: center;
      gap: 10px;
    }

    .section-intro {
      font-size: 0.95rem;
      color: var(--text-muted);
      margin-bottom: 20px;
    }

    .vocab-grid {
      display: grid;
      grid-template-columns: repeat(auto-fill, minmax(330px, 1fr));
      gap: 16px;
    }

    .vocab-card {
      background: var(--bg-card);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      padding: 16px 18px;
      box-shadow: var(--shadow-sm);
      transition: border-color 0.25s ease, box-shadow 0.25s ease, background-color 0.25s ease;
      position: relative;
      display: flex;
      flex-direction: column;
    }

    .vocab-card.highlight-flash {
      border-color: #3b82f6;
      box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.25);
      background-color: #eff6ff;
    }

    .vocab-top-row {
      display: flex;
      align-items: flex-start;
      justify-content: space-between;
      gap: 12px;
      margin-bottom: 8px;
    }

    .vocab-heading-wrap {
      display: flex;
      align-items: center;
      flex-wrap: wrap;
      gap: 8px;
      flex-grow: 1;
    }

    .vocab-word {
      font-size: 1.15rem;
      font-weight: 800;
      color: var(--text-main);
      letter-spacing: -0.01em;
      line-height: 1.25;
    }

    .vocab-translation {
      font-size: 0.82rem;
      font-weight: 700;
      color: var(--accent-green);
      background: var(--accent-green-bg);
      padding: 3px 9px;
      border-radius: var(--radius-pill);
      border: 1px solid var(--accent-green-border);
      display: inline-flex;
      align-items: center;
      line-height: 1.2;
    }

    /* Speaker Audio Button - always anchored on top-right */
    .btn-audio {
      width: 32px;
      height: 32px;
      border-radius: var(--radius-pill);
      background: var(--primary-light);
      border: 1px solid var(--primary-border);
      color: var(--primary);
      display: inline-flex;
      align-items: center;
      justify-content: center;
      transition: all 0.2s ease;
      cursor: pointer;
      flex-shrink: 0;
      margin-left: auto;
    }

    .btn-audio:hover {
      background: var(--primary);
      color: #ffffff;
      transform: scale(1.1);
      box-shadow: 0 2px 8px rgba(37, 99, 235, 0.25);
    }

    .btn-audio svg {
      width: 15px;
      height: 15px;
      fill: currentColor;
    }

    .btn-audio.playing {
      background: var(--accent-green);
      color: #ffffff;
      border-color: var(--accent-green);
      animation: pulse 1s infinite;
    }

    @keyframes pulse {
      0% { transform: scale(1); }
      50% { transform: scale(1.1); }
      100% { transform: scale(1); }
    }

    .vocab-explanation {
      font-size: 0.9rem;
      color: var(--text-main);
      margin-bottom: 12px;
      line-height: 1.45;
      flex-grow: 1;
    }

    .vocab-example {
      font-size: 0.84rem;
      color: var(--text-muted);
      background: var(--bg-subtle);
      padding: 8px 12px;
      border-radius: var(--radius-sm);
      border-left: 3px solid var(--primary);
      line-height: 1.45;
      margin-top: auto;
    }

    .vocab-example-label {
      font-weight: 700;
      font-style: normal;
      color: var(--text-main);
      margin-right: 4px;
    }

    .vocab-example strong {
      color: var(--primary);
      font-style: normal;
    }

    /* -------------------------------------------------------------
       QUESTIONS LISTS (Comprehension & Discussion)
    ------------------------------------------------------------- */
    .questions-card {
      background: var(--bg-card);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-xl);
      padding: 30px 32px;
      box-shadow: var(--shadow-sm);
    }

    .questions-list {
      list-style: none;
      display: flex;
      flex-direction: column;
      gap: 16px;
    }

    .question-item {
      display: flex;
      align-items: flex-start;
      gap: 16px;
      font-size: 1.05rem;
      color: var(--text-main);
      line-height: 1.55;
    }

    .q-number {
      flex-shrink: 0;
      width: 32px;
      height: 32px;
      border-radius: var(--radius-pill);
      background: var(--bg-subtle);
      color: var(--text-main);
      border: 1px solid var(--border-color);
      font-weight: 700;
      font-size: 0.9rem;
      display: flex;
      align-items: center;
      justify-content: center;
      margin-top: 2px;
    }

    .q-number.discussion {
      background: var(--primary-light);
      color: var(--primary);
      border-color: var(--primary-border);
    }

    .question-text {
      flex-grow: 1;
      padding-top: 3px;
    }

    /* Responsive */
    @media (max-width: 1024px) {
      .hub-hero {
        grid-template-columns: 1fr;
        gap: 24px;
        padding: 28px 0 16px;
      }
      .hub-title {
        font-size: 2.15rem;
      }
      .hub-level-tabs {
        display: flex;
        flex-direction: column;
        gap: 8px;
      }
    }

    @media (max-width: 640px) {
      .hub-hero {
        padding: 20px 0 12px;
        gap: 18px;
      }
      .hub-title { font-size: 1.75rem; }
      .hub-hero-pills { gap: 6px; }
      .hub-hero-pill { font-size: 0.74rem; padding: 3px 8px; }
      .hub-level-card { padding: 16px; }
      .article-main-title { font-size: 1.65rem; }
      .article-header { padding: 22px 20px; }
      .reading-box { padding: 22px 18px; }
      .reading-content p { font-size: 1.05rem; line-height: 1.75; }
      .questions-card { padding: 22px 18px; }
      .vocab-grid { grid-template-columns: 1fr; }
      .vocab-top-row { gap: 8px; }
      .hub-level-tabs { display: flex; flex-direction: column; gap: 8px; }
      .hub-level-btn { padding: 10px 14px; }
      .hub-level-hint { font-size: 0.80rem; }
      .hub-controls { flex-direction: column; align-items: stretch; gap: 14px; padding: 14px; }
      .category-filters { justify-content: flex-start; }
      .sort-box { justify-content: space-between; }
    }
  
    /* Floating Action Bar Component */
    .article-top-bar {
      position: sticky;
      top: 92px;
      z-index: 100;
      margin-bottom: 16px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
      background: rgba(255, 255, 255, 0.94);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-pill);
      padding: 8px 12px;
      box-shadow: 0 4px 20px -2px rgba(15, 23, 42, 0.08), 0 2px 6px -1px rgba(15, 23, 42, 0.04);
      transition: box-shadow 0.2s ease, transform 0.2s ease;
    }

    .btn-floating-back {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      padding: 8px 16px;
      background: #ffffff;
      border: 1px solid var(--border-color);
      border-radius: var(--radius-pill);
      font-size: 0.92rem;
      font-weight: 600;
      color: var(--text-muted);
      box-shadow: var(--shadow-sm);
      transition: all 0.2s ease;
      text-decoration: none;
      white-space: nowrap;
      flex-shrink: 0;
    }

    .btn-floating-back:hover {
      color: var(--primary);
      border-color: var(--primary-border);
      background: var(--primary-light);
      transform: translateX(-2px);
    }

    .btn-floating-back svg {
      transition: transform 0.2s ease;
    }

    .btn-floating-back:hover svg {
      transform: translateX(-2px);
    }

    .btn-back-text-short {
      display: none;
    }

    .floating-bar-actions {
      display: inline-flex;
      align-items: center;
      gap: 10px;
      flex-shrink: 0;
    }

    .top-bar-level-label {
      font-size: 0.84rem;
      font-weight: 700;
      color: var(--text-muted);
      white-space: nowrap;
    }

    .level-switcher-tabs {
      display: inline-flex;
      align-items: center;
      background: var(--bg-subtle);
      border: 1px solid var(--border-color);
      padding: 4px;
      border-radius: var(--radius-pill);
      gap: 4px;
    }

    .level-tab-btn {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      padding: 8px 18px;
      border-radius: var(--radius-pill);
      font-size: 0.92rem;
      font-weight: 700;
      color: var(--text-muted);
      background: transparent;
      border: none;
      cursor: pointer;
      transition: all 0.22s ease;
      user-select: none;
      white-space: nowrap;
    }

    .level-tab-btn:hover {
      color: var(--text-main);
    }

    .level-tab-btn.active {
      background: #ffffff;
      color: var(--primary);
      box-shadow: var(--shadow-sm);
    }

    .level-tab-btn.active#tab-level-a1 {
      color: #059669;
      box-shadow: 0 2px 5px rgba(5, 150, 105, 0.15);
    }

    .level-tab-btn.active#tab-level-a2 {
      color: #0d9488;
      box-shadow: 0 2px 5px rgba(13, 148, 136, 0.15);
    }

    .level-tab-btn.active#tab-level-b1 {
      color: #4338ca;
      box-shadow: 0 2px 5px rgba(67, 56, 202, 0.15);
    }

    .lvl-label-short {
      display: none;
    }

    @media (max-width: 640px) {
      .article-top-bar {
        top: 10px;
        padding: 6px 8px;
        gap: 8px;
      }
      .top-bar-level-label {
        display: none;
      }
      .btn-floating-back {
        padding: 7px 10px;
        font-size: 0.82rem;
        gap: 4px;
      }
      .btn-back-text-full {
        display: none;
      }
      .btn-back-text-short {
        display: inline;
      }
      .level-switcher-tabs {
        padding: 3px;
        gap: 3px;
      }
      .level-tab-btn {
        padding: 6px 10px;
        font-size: 0.82rem;
        gap: 4px;
      }
      .lvl-label-full {
        display: none;
      }
      .lvl-label-short {
        display: inline;
      }
    }

    /* ==========================================================================
       GLOBAL SITE HEADER (BRAND NAVIGATION)
       ========================================================================== */
    .site-header {
      background: #ffffff;
      border-bottom: 1px solid var(--border-color);
      box-shadow: 0 2px 8px -2px rgba(15, 23, 42, 0.04);
      position: sticky;
      top: 0;
      z-index: 150;
      width: 100%;
    }

    .site-header-container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 20px;
      height: 76px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 20px;
    }
    @media (min-width: 1440px) {
      .site-header-container {
        max-width: 1440px;
        padding: 0 24px;
      }
    }
    @media (min-width: 1536px) {
      .site-header-container {
        max-width: 1536px;
        padding: 0 32px;
      }
    }

    .site-brand-wrapper {
      display: inline-flex;
      align-items: center;
      gap: 12px;
      flex-shrink: 0;
    }

    .site-brand-link {
      display: inline-flex;
      align-items: center;
      text-decoration: none;
      flex-shrink: 0;
    }

    .site-brand-logo {
      height: 48px;
      width: auto;
      display: block;
      object-fit: contain;
    }

    .site-brand-badge {
      font-size: 0.74rem;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.06em;
      padding: 4px 10px;
      background: #eff6ff;
      color: #2563eb;
      border: 1px solid #bfdbfe;
      border-radius: var(--radius-pill);
      white-space: nowrap;
      text-decoration: none;
      transition: all 0.15s ease;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
    }

    .site-brand-badge:hover {
      background: #dbeafe;
      color: #1d4ed8;
      border-color: #93c5fd;
      transform: translateY(-1px);
    }

    .site-nav-desktop {
      display: flex;
      align-items: center;
      gap: 4px;
      list-style: none;
    }

    .site-nav-link {
      color: var(--text-muted);
      font-size: 0.90rem;
      font-weight: 600;
      padding: 8px 12px;
      border-radius: var(--radius-sm);
      transition: all 0.15s ease;
      white-space: nowrap;
      text-decoration: none;
    }

    .site-nav-link:hover {
      color: #0f172a;
      background: var(--bg-subtle);
    }

    .site-nav-link.active {
      color: #2563eb;
      background: #eff6ff;
      font-weight: 700;
    }

    .site-cta-btn {
      background: #fa5a29;
      color: #ffffff !important;
      font-size: 0.88rem;
      font-weight: 700;
      padding: 8px 18px;
      border-radius: var(--radius-pill);
      text-decoration: none;
      white-space: nowrap;
      transition: all 0.2s ease;
      box-shadow: 0 2px 6px rgba(250, 90, 41, 0.25);
      margin-left: 6px;
      display: inline-flex;
      align-items: center;
      gap: 6px;
    }

    .site-cta-btn:hover {
      background: #e04818;
      transform: translateY(-1px);
      box-shadow: 0 4px 12px rgba(250, 90, 41, 0.35);
    }

    /* Mobile Hamburger Button */
    .mobile-menu-btn {
      display: none;
      background: none;
      border: 1px solid var(--border-color);
      padding: 8px;
      border-radius: var(--radius-sm);
      color: var(--text-main);
      cursor: pointer;
      line-height: 0;
    }

    .mobile-menu-drawer {
      display: none;
      position: absolute;
      top: 100%;
      left: 0;
      right: 0;
      background: #ffffff;
      border-bottom: 2px solid var(--border-color);
      box-shadow: 0 12px 24px -6px rgba(0, 0, 0, 0.1);
      padding: 16px 20px 24px;
      z-index: 140;
      max-height: calc(100vh - 76px);
      overflow-y: auto;
    }

    .mobile-menu-drawer.open {
      display: block;
    }

    .mobile-nav-list {
      list-style: none;
      display: flex;
      flex-direction: column;
      gap: 6px;
    }

    .mobile-nav-list .site-nav-link {
      display: block;
      padding: 12px 14px;
      font-size: 1rem;
      border-radius: 8px;
    }

    .mobile-cta-wrapper {
      margin-top: 14px;
      padding-top: 14px;
      border-top: 1px solid var(--border-color);
    }

    .mobile-cta-wrapper .site-cta-btn {
      display: flex;
      justify-content: center;
      width: 100%;
      margin: 0;
      padding: 12px;
      font-size: 1rem;
    }

    @media (max-width: 1024px) {
      .site-nav-desktop {
        display: none;
      }
      .mobile-menu-btn {
        display: block;
      }
      .site-brand-logo {
        height: 38px;
      }
    }

    /* ==========================================================================
       GLOBAL SITE FOOTER
       ========================================================================== */
    .site-footer {
      background: #0f172a;
      color: #94a3b8;
      border-top: 1px solid #1e293b;
      padding: 56px 0 32px;
      margin-top: 40px;
      width: 100%;
    }

    .site-footer-container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 24px;
    }
    @media (min-width: 1440px) {
      .site-footer-container {
        max-width: 1440px;
      }
    }
    @media (min-width: 1536px) {
      .site-footer-container {
        max-width: 1536px;
        padding: 0 32px;
      }
    }

    .site-footer-grid {
      display: grid;
      grid-template-columns: 1.4fr 1fr 1fr;
      gap: 40px;
      padding-bottom: 40px;
      border-bottom: 1px solid #1e293b;
    }

    .footer-col {
      display: flex;
      flex-direction: column;
      height: 100%;
    }

    .footer-brand-title {
      font-size: 1.15rem;
      font-weight: 700;
      color: #ffffff;
      margin-bottom: 12px;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .footer-brand-desc {
      font-size: 0.88rem;
      line-height: 1.6;
      color: #94a3b8;
      margin: 0 0 20px 0;
      max-width: 440px;
    }

    .footer-linkedin-card {
      display: flex;
      align-items: center;
      gap: 12px;
      background: rgba(255, 255, 255, 0.03);
      border: 1px solid #1e293b;
      border-radius: 10px;
      padding: 10px 14px;
      margin-top: auto;
      max-width: 380px;
      text-decoration: none;
      transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    }

    .footer-linkedin-card:hover {
      background: rgba(10, 102, 194, 0.08);
      border-color: rgba(10, 102, 194, 0.45);
      transform: translateY(-2px);
      box-shadow: 0 4px 12px -2px rgba(10, 102, 194, 0.2);
    }

    .footer-linkedin-icon {
      width: 32px;
      height: 32px;
      border-radius: 8px;
      background: #0a66c2;
      color: #ffffff;
      display: flex;
      align-items: center;
      justify-content: center;
      flex-shrink: 0;
      transition: transform 0.2s ease;
    }

    .footer-linkedin-card:hover .footer-linkedin-icon {
      transform: scale(1.05);
    }

    .footer-linkedin-text {
      display: flex;
      flex-direction: column;
      min-width: 0;
    }

    .footer-linkedin-title {
      font-size: 0.82rem;
      font-weight: 700;
      color: #f1f5f9;
      display: flex;
      align-items: center;
      gap: 6px;
    }

    .footer-linkedin-arrow {
      color: #60a5fa;
      transition: transform 0.2s ease;
    }

    .footer-linkedin-card:hover .footer-linkedin-arrow {
      transform: translateX(3px);
      color: #93c5fd;
    }

    .footer-linkedin-sub {
      font-size: 0.72rem;
      color: #94a3b8;
      margin-top: 1px;
    }

    .footer-col-title {
      font-size: 0.82rem;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.08em;
      color: #ffffff;
      margin: 0 0 16px 0;
    }

    .footer-links-list {
      list-style: none;
      display: flex;
      flex-direction: column;
      gap: 12px;
      margin: 0 0 20px 0;
      padding: 0;
    }

    .footer-links-list a {
      font-size: 0.90rem;
      color: #94a3b8;
      text-decoration: none;
      transition: color 0.15s ease, transform 0.15s ease;
      display: inline-block;
    }

    .footer-links-list a:hover {
      color: #ffffff;
      transform: translateX(3px);
    }

    .footer-cta-emerald {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      background: rgba(16, 185, 129, 0.14);
      border: 1px solid rgba(16, 185, 129, 0.45);
      color: #6ee7b7;
      font-size: 0.82rem;
      font-weight: 700;
      padding: 11px 14px;
      border-radius: 9px;
      text-decoration: none;
      margin-top: auto;
      width: 100%;
      max-width: 320px;
      box-sizing: border-box;
      transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
      box-shadow: 0 2px 8px -2px rgba(16, 185, 129, 0.2);
    }

    .footer-cta-emerald:hover {
      background: #059669;
      border-color: #059669;
      color: #ffffff;
      transform: translateY(-2px);
      box-shadow: 0 6px 18px rgba(5, 150, 105, 0.4);
    }

    .footer-cta-emerald .footer-btn-arrow {
      transition: transform 0.2s ease;
    }

    .footer-cta-emerald:hover .footer-btn-arrow {
      transform: translateX(3px);
    }

    .footer-cta-contact {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      background: rgba(255, 255, 255, 0.04);
      border: 1px solid #1e293b;
      color: #e2e8f0;
      font-size: 0.82rem;
      font-weight: 600;
      padding: 11px 14px;
      border-radius: 9px;
      text-decoration: none;
      margin-top: auto;
      width: 100%;
      max-width: 320px;
      box-sizing: border-box;
      transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    }

    .footer-cta-contact:hover {
      background: rgba(255, 255, 255, 0.09);
      border-color: #334155;
      color: #ffffff;
      transform: translateY(-2px);
      box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
    }

    .footer-cta-contact .footer-btn-arrow {
      transition: transform 0.2s ease;
      color: #94a3b8;
    }

    .footer-cta-contact:hover .footer-btn-arrow {
      transform: translateX(3px);
      color: #ffffff;
    }

    .site-footer-bottom {
      padding-top: 24px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      flex-wrap: wrap;
      gap: 12px;
      font-size: 0.82rem;
      color: #64748b;
    }

    .footer-legal-links {
      display: flex;
      gap: 16px;
    }

    .footer-legal-links a {
      color: #64748b;
      text-decoration: none;
      transition: color 0.15s ease;
    }

    .footer-legal-links a:hover {
      color: #94a3b8;
    }

    @media (max-width: 960px) {
      .site-footer-grid {
        grid-template-columns: 1fr;
        gap: 32px;
      }
    }

    @media (max-width: 640px) {
      .site-footer {
        padding: 40px 0 24px;
      }
      .site-footer-grid {
        gap: 24px;
      }
      .site-footer-bottom {
        flex-direction: column;
        text-align: center;
        gap: 10px;
      }
    }