:root {
    --green: #2d8a4e;
    --green-light: #e8f5ed;
    --green-mid: #4caf72;
    --yellow: #f5c518;
    --yellow-light: #fffbe6;
    --red: #e05252;
    --blue: #3a7bd5;
    --blue-light: #e8f0fb;
    --bg: #f7f9f8;
    --card: #ffffff;
    --text: #1a2e22;
    --muted: #6b7f72;
    --border: #d0e4d8;
    --shadow: 0 4px 24px rgba(45,138,78,0.10);
    --radius: 18px;
  }
  * { box-sizing: border-box; margin: 0; padding: 0; }
  body {
    font-family: 'Nunito', sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
  }

  /* Header */
  .header {
    background: linear-gradient(135deg, #1a5c32 0%, #2d8a4e 60%, #4caf72 100%);
    color: white;
    padding: 28px 32px 20px;
    text-align: center;
    position: relative;
    overflow: hidden;
  }
  .header::before {
    content: '';
    position: absolute;
    top: -40px; right: -40px;
    width: 160px; height: 160px;
    background: rgba(255,255,255,0.06);
    border-radius: 50%;
  }
  .header::after {
    content: '';
    position: absolute;
    bottom: -30px; left: -30px;
    width: 120px; height: 120px;
    background: rgba(255,255,255,0.05);
    border-radius: 50%;
  }
  .header h1 {
    font-family: 'Playfair Display', serif;
    font-size: 2rem;
    letter-spacing: 0.01em;
    position: relative;
    z-index: 1;
  }
  .header p {
    font-size: 0.95rem;
    opacity: 0.82;
    margin-top: 6px;
    position: relative;
    z-index: 1;
  }

  /* Tab Nav */
  .tab-nav {
    display: flex;
    gap: 0;
    background: #e2ede7;
    overflow-x: auto;
    scrollbar-width: none;
    padding: 0 16px;
    border-bottom: 2px solid var(--border);
  }
  .tab-nav::-webkit-scrollbar { display: none; }
  .tab-btn {
    flex-shrink: 0;
    padding: 14px 22px;
    border: none;
    background: transparent;
    font-family: 'Nunito', sans-serif;
    font-weight: 700;
    font-size: 0.88rem;
    color: var(--muted);
    cursor: pointer;
    border-bottom: 3px solid transparent;
    transition: all 0.22s;
    white-space: nowrap;
  }
  .tab-btn:hover { color: var(--green); background: rgba(45,138,78,0.06); }
  .tab-btn.active {
    color: var(--green);
    border-bottom-color: var(--green);
    background: rgba(45,138,78,0.09);
  }

  /* Main Content */
  .main { max-width: 900px; margin: 0 auto; padding: 28px 16px 60px; }

  .tab-panel { display: none; }
  .tab-panel.active { display: block; animation: fadeIn 0.3s ease; }
  @keyframes fadeIn { from { opacity:0; transform: translateY(10px); } to { opacity:1; transform: translateY(0); } }

  /* Section Titles */
  .section-label {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: var(--green);
    color: white;
    font-weight: 800;
    font-size: 0.78rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    padding: 5px 14px;
    border-radius: 20px;
    margin-bottom: 14px;
  }

  /* Reading Card */
  .reading-card {
    background: var(--card);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 28px 32px;
    margin-bottom: 28px;
    border: 1.5px solid var(--border);
  }
  .reading-card h2 {
    font-size: 1.45rem;
    color: var(--green);
    margin-bottom: 6px;
    font-family: 'Playfair Display', serif;
  }
  .reading-card .subtitle {
    font-size: 0.83rem;
    color: var(--muted);
    margin-bottom: 18px;
  }
  .reading-body { line-height: 1.9; font-size: 0.97rem; }
  .reading-body p { margin-bottom: 12px; }
  .reading-body ul { padding-left: 18px; margin-bottom: 10px; }
  .reading-body li { margin-bottom: 5px; }
  .reading-body .job-block {
    background: var(--green-light);
    border-left: 4px solid var(--green);
    border-radius: 10px;
    padding: 14px 18px;
    margin-bottom: 14px;
  }
  .reading-body .job-block h3 {
    color: var(--green);
    font-size: 1rem;
    margin-bottom: 8px;
    font-weight: 800;
  }

  /* Quiz */
  .quiz-card {
    background: var(--card);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 28px 32px;
    margin-bottom: 28px;
    border: 1.5px solid var(--border);
  }
  .question-block { margin-bottom: 28px; }
  .question-block:last-child { margin-bottom: 0; }
  .question-text {
    font-weight: 700;
    font-size: 1rem;
    margin-bottom: 14px;
    line-height: 1.6;
  }
  .options { display: flex; flex-direction: column; gap: 10px; }
  .option-btn {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 13px 18px;
    border-radius: 12px;
    border: 2px solid var(--border);
    background: var(--bg);
    font-family: 'Nunito', sans-serif;
    font-size: 0.93rem;
    font-weight: 600;
    color: var(--text);
    cursor: pointer;
    text-align: left;
    transition: all 0.18s;
  }
  .option-btn:hover:not(:disabled) { border-color: var(--green-mid); background: var(--green-light); }
  .option-btn .opt-letter {
    flex-shrink: 0;
    width: 26px; height: 26px;
    border-radius: 50%;
    background: var(--border);
    display: flex; align-items: center; justify-content: center;
    font-weight: 800; font-size: 0.8rem;
    transition: all 0.18s;
  }
  .option-btn.correct { border-color: var(--green); background: var(--green-light); }
  .option-btn.correct .opt-letter { background: var(--green); color: white; }
  .option-btn.wrong { border-color: var(--red); background: #fdeaea; }
  .option-btn.wrong .opt-letter { background: var(--red); color: white; }
  .option-btn:disabled { cursor: default; }

  /* T/F */
  .tf-row {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    border-radius: 12px;
    border: 2px solid var(--border);
    background: var(--bg);
    margin-bottom: 10px;
    flex-wrap: wrap;
  }
  .tf-row .tf-text { flex: 1; font-size: 0.93rem; font-weight: 600; min-width: 180px; }
  .tf-btns { display: flex; gap: 8px; }
  .tf-btn {
    padding: 6px 18px;
    border-radius: 8px;
    border: 2px solid var(--border);
    background: white;
    font-family: 'Nunito', sans-serif;
    font-weight: 700;
    font-size: 0.85rem;
    cursor: pointer;
    transition: all 0.15s;
  }
  .tf-btn:hover:not(:disabled) { border-color: var(--green); color: var(--green); }
  .tf-btn.correct { background: var(--green); color: white; border-color: var(--green); }
  .tf-btn.wrong { background: var(--red); color: white; border-color: var(--red); }

  .feedback {
    margin-top: 10px;
    font-size: 0.85rem;
    font-weight: 700;
    padding: 6px 14px;
    border-radius: 8px;
    display: none;
  }
  .feedback.show { display: inline-block; }
  .feedback.ok { background: var(--green-light); color: var(--green); }
  .feedback.no { background: #fdeaea; color: var(--red); }

  /* Vocabulary */
  .vocab-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 16px;
    margin-bottom: 28px;
  }
  .vocab-card {
    background: var(--card);
    border-radius: 16px;
    padding: 18px 20px;
    border: 1.5px solid var(--border);
    box-shadow: 0 2px 12px rgba(45,138,78,0.07);
    transition: box-shadow 0.2s, transform 0.2s;
  }
  .vocab-card:hover { box-shadow: 0 6px 24px rgba(45,138,78,0.15); transform: translateY(-2px); }
  .vocab-top { display: flex; align-items: center; justify-content: space-between; margin-bottom: 8px; }
  .vocab-word { font-size: 1.3rem; font-weight: 900; color: var(--green); }
  .vocab-pos {
    font-size: 0.73rem;
    background: var(--yellow-light);
    color: #b07a00;
    border: 1.5px solid var(--yellow);
    padding: 2px 10px;
    border-radius: 20px;
    font-weight: 700;
    letter-spacing: 0.04em;
  }
  .vocab-phonetic { font-size: 0.82rem; color: var(--muted); margin-bottom: 6px; }
  .vocab-def { font-size: 0.88rem; font-weight: 600; margin-bottom: 8px; color: var(--text); }
  .vocab-example {
    font-size: 0.83rem;
    color: var(--muted);
    font-style: italic;
    line-height: 1.6;
    padding: 8px 12px;
    background: var(--green-light);
    border-radius: 8px;
    margin-bottom: 10px;
  }
  .speak-btn {
    display: flex;
    align-items: center;
    gap: 7px;
    padding: 7px 16px;
    border-radius: 20px;
    border: 2px solid var(--green);
    background: white;
    font-family: 'Nunito', sans-serif;
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--green);
    cursor: pointer;
    transition: all 0.18s;
  }
  .speak-btn:hover { background: var(--green); color: white; }
  .speak-btn svg { width: 14px; height: 14px; }

  /* Score Bar */
  .score-area {
    margin-top: 22px;
    padding: 16px 20px;
    background: var(--green-light);
    border-radius: 12px;
    border: 1.5px solid var(--green-mid);
    display: none;
    align-items: center;
    gap: 14px;
    font-weight: 700;
    font-size: 1rem;
    color: var(--green);
  }
  .score-area.show { display: flex; }
  .score-emoji { font-size: 1.6rem; }

  /* Notes table */
  .notes-table { width: 100%; border-collapse: collapse; margin: 14px 0; font-size: 0.9rem; }
  .notes-table th { background: var(--green); color: white; padding: 10px 14px; text-align: left; }
  .notes-table td { padding: 10px 14px; border-bottom: 1px solid var(--border); }
  .notes-table tr:nth-child(even) td { background: var(--green-light); }

  /* flight table */
  .flight-table { width: 100%; border-collapse: collapse; font-size: 0.85rem; margin: 14px 0; }
  .flight-table th { background: #1a1a2e; color: #f5c518; padding: 8px 10px; text-align: left; }
  .flight-table td { padding: 8px 10px; border-bottom: 1px solid var(--border); }
  .flight-table tr:nth-child(even) td { background: #f0f0f8; }
  .status-canceled { color: var(--red); font-weight: 700; }
  .status-delayed { color: #e07a20; font-weight: 700; }
  .status-ontime { color: var(--green); font-weight: 700; }

  @media (max-width: 600px) {
    .reading-card, .quiz-card { padding: 18px 16px; }
    .vocab-grid { grid-template-columns: 1fr; }
    .header h1 { font-size: 1.4rem; }
  }