:root{
      --bg:#f7f8fc;--card:#ffffff;--ink:#18212f;--muted:#5f6b7a;--line:#d9e1ec;--brand:#4f46e5;--brand-2:#7c3aed;--ok:#0f9d58;--warn:#ef6c00;--bad:#c62828;--soft:#eef2ff;--soft-2:#f3e8ff;--shadow:0 12px 30px rgba(24,33,47,.08);--radius:18px;
    }
    *{box-sizing:border-box} html,body{margin:0;padding:0;background:var(--bg);color:var(--ink);font-family:Inter,system-ui,sans-serif}
    body[data-module-id="main"]{min-height:100vh} button,input,textarea{font:inherit} :focus-visible{outline:3px solid #111827;outline-offset:2px}
    #app-shell{max-width:1060px;margin:0 auto;padding:76px 16px 96px}
    header.lesson-header{text-align:center;margin-bottom:14px}
    .eyebrow{display:inline-block;background:var(--soft);color:var(--brand);padding:6px 12px;border-radius:999px;font-weight:700;font-size:.86rem}
    h1{margin:14px 0 8px;font-size:clamp(1.8rem,3vw,2.8rem);line-height:1.12}.subtitle{max-width:780px;margin:0 auto;color:var(--muted)}
    .frame{background:var(--card);border:1px solid var(--line);border-radius:24px;box-shadow:var(--shadow);overflow:hidden}
    .topbar{padding:14px 18px;border-bottom:1px solid var(--line);display:flex;align-items:center;gap:14px;justify-content:space-between;background:linear-gradient(90deg,var(--soft),#fff)}
    .progress-wrap{flex:1;max-width:460px}.progress-meta{display:flex;justify-content:space-between;font-size:.9rem;color:var(--muted);margin-bottom:7px}
    .progress{height:10px;background:#e8edf5;border-radius:999px;overflow:hidden}.progress-bar{height:100%;width:0;background:linear-gradient(90deg,var(--brand),var(--brand-2));transition:width .25s ease}.chip{padding:8px 12px;border:1px solid var(--line);border-radius:999px;background:#fff;color:var(--muted);font-size:.88rem;font-weight:700}
    main#lesson-content{height:min(72vh,820px);overflow-y:auto;padding:20px}.lesson-page{display:none;animation:fade .22s ease}.lesson-page.active{display:block}
    @keyframes fade{from{opacity:.2;transform:translateY(6px)}to{opacity:1;transform:translateY(0)}}
    .page-card{background:linear-gradient(180deg,#fff,#fcfdff);border:1px solid var(--line);border-radius:var(--radius);padding:22px}.page-header{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:14px;flex-wrap:wrap}.page-tag{background:var(--soft);color:var(--brand);padding:6px 10px;border-radius:999px;font-size:.82rem;font-weight:800}.page-title{margin:0;font-size:1.45rem}.page-copy{color:var(--muted);margin:0 0 14px}
    .intro-grid,.two-col,.triple,.attention-box{display:grid;gap:14px}.intro-grid{grid-template-columns:1.1fr .9fr}.two-col,.attention-box{grid-template-columns:1fr 1fr}.triple{grid-template-columns:repeat(3,1fr)}
    @media (max-width:840px){.intro-grid,.two-col,.triple,.attention-box{grid-template-columns:1fr}}
    .panel{border:1px solid var(--line);border-radius:16px;padding:16px;background:#fff}.panel h3,.panel h4{margin:0 0 8px}.mini-list{margin:0;padding-left:18px}.mini-list li{margin:6px 0}
    .visual-box{border:1px solid var(--line);border-radius:16px;background:linear-gradient(135deg,var(--soft),var(--soft-2));padding:16px;min-height:190px;display:flex;align-items:center;justify-content:center;position:relative;overflow:hidden}
    .equation-card{background:#fff;border:1px solid rgba(79,70,229,.18);border-radius:18px;padding:18px 20px;box-shadow:0 10px 24px rgba(79,70,229,.08);text-align:center;min-width:220px}
    .equation{font-size:2rem;font-weight:800;letter-spacing:.02em}.math-note{margin-top:8px;color:var(--muted);font-size:.95rem}.bubble{position:absolute;border-radius:999px;opacity:.18}.b1{width:110px;height:110px;background:#8b5cf6;top:-18px;right:-10px}.b2{width:90px;height:90px;background:#4f46e5;bottom:-18px;left:-16px}
    .btn,.option-btn,.nav-btn{border:none;border-radius:14px;padding:12px 16px;font-weight:700;cursor:pointer;transition:transform .08s ease,background .2s ease,opacity .2s ease,border-color .2s ease}.btn:active,.option-btn:active,.nav-btn:active{transform:translateY(1px)}
    .btn-primary,.nav-btn.next{background:linear-gradient(90deg,var(--brand),var(--brand-2));color:#fff}.btn-secondary,.nav-btn.prev{background:#fff;color:var(--ink);border:1px solid var(--line)}.btn-ghost{background:var(--soft);color:var(--brand)}.btn[disabled],.nav-btn[disabled]{opacity:.5;cursor:not-allowed}
    .feedback{margin-top:12px;padding:12px 14px;border-radius:14px;border:1px solid var(--line);background:#fff;display:none}.feedback.show{display:block}.feedback.ok{border-color:#b7e1c3;background:#f2fbf5;color:#146c2e}.feedback.warn{border-color:#ffd9b0;background:#fff6eb;color:#9a4c08}.feedback.info{border-color:#cfd8ff;background:#f6f8ff;color:#3243b5}
    .option-grid{display:grid;gap:12px}.option-btn{width:100%;text-align:left;background:#fff;border:1px solid var(--line);color:var(--ink)}.option-btn:hover{background:#f8fbff}.option-btn.selected{border-color:var(--brand);background:var(--soft)}.option-btn.correct{border-color:var(--ok);background:#edf9f0}.option-btn.incorrect{border-color:var(--bad);background:#fff1f1}.option-prefix{display:inline-flex;width:28px;height:28px;border-radius:999px;align-items:center;justify-content:center;background:#eef1f6;margin-right:10px;font-weight:800}
    .sortable{display:flex;gap:10px;flex-wrap:wrap;margin-top:10px}.pill{padding:10px 12px;border-radius:999px;border:1px solid var(--line);background:#fff;cursor:pointer;font-weight:700}.pill.active{background:var(--soft);border-color:var(--brand);color:var(--brand)}
    .equation-steps{display:grid;gap:10px}.step{display:flex;align-items:center;gap:10px;padding:12px;border:1px solid var(--line);border-radius:14px;background:#fff}.step-num{width:32px;height:32px;border-radius:999px;background:var(--soft);display:flex;align-items:center;justify-content:center;font-weight:800;color:var(--brand)}
    .balance-scale{display:grid;grid-template-columns:1fr 1fr;gap:12px;width:100%;max-width:420px;align-items:end}.scale-pan{background:#fff;border:1px solid var(--line);border-radius:16px;padding:12px;text-align:center;min-height:88px}.beam{grid-column:1 / span 2;height:8px;background:linear-gradient(90deg,var(--brand),var(--brand-2));border-radius:999px;position:relative}.beam:after{content:'';position:absolute;left:50%;top:-26px;transform:translateX(-50%);width:12px;height:34px;background:#6d28d9;border-radius:12px}
    .card-stack{display:grid;gap:10px;width:100%}.match-row{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:10px 12px;background:#fff;border:1px solid var(--line);border-radius:12px}.arrow{font-weight:800;color:var(--brand)}
    .nav-bar{position:sticky;bottom:0;background:rgba(247,248,252,.96);backdrop-filter:blur(10px);border-top:1px solid var(--line);padding:12px 18px;display:flex;align-items:center;justify-content:space-between;gap:14px}.nav-group{display:flex;gap:10px}.nav-status{font-size:.92rem;color:var(--muted);font-weight:700}
    .kpi{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}@media (max-width:700px){.kpi{grid-template-columns:1fr}} .score-big{font-size:2.4rem;font-weight:800;margin:8px 0}.name-row{display:flex;gap:10px;flex-wrap:wrap;align-items:center}.name-row input{flex:1;min-width:220px;padding:12px 14px;border-radius:12px;border:1px solid var(--line)}
    #certificate{margin-top:16px;border:8px solid #e9ddff;border-radius:24px;padding:28px;background:linear-gradient(180deg,#fff,#fbf8ff);text-align:center} #certificate h3{margin:0 0 10px;font-size:1.8rem}.cert-name{font-size:1.4rem;font-weight:800;margin:16px 0 8px}.cert-meta,.sources{color:var(--muted)} .sources li{margin:6px 0}
    footer.lesson-footer{text-align:center;color:var(--muted);padding:16px;font-size:.88rem}
    @media print{body{background:#fff}#app-auth-root,header.lesson-header,.topbar,.nav-bar,.results-controls,footer.lesson-footer{display:none !important}#app-shell{padding:0;margin:0;max-width:none}.frame,.page-card{border:none;box-shadow:none}.lesson-page{display:none !important}.lesson-page.active[data-page='Results']{display:block !important}#certificate{page-break-inside:avoid;border-width:6px;margin:0 auto;max-width:900px}}

body {
    min-height: 100vh;
    overflow-y: auto !important;
  }
  .content-area,
  .content,
  .lesson-content,
  .main-content {
    overflow-y: auto !important;
    min-height: calc(100vh - 140px);
  }
  .bottom-bar, .nav-container, .nav-bar, .story-nav {
    position: sticky;
    bottom: 0;
    left: 0;
    right: 0;
    width: 100% !important;
    display: flex !important;
    visibility: visible !important;
    box-sizing: border-box !important;
    max-width: 100% !important;
    flex-wrap: wrap;
  }