*{box-sizing:border-box}body{font-family:system-ui,sans-serif;max-width:720px;margin:0 auto;padding:2rem;background:#0f172a;color:#e2e8f0}header{margin-bottom:2rem}h1{margin:0;color:#38bdf8}section{background:#1e293b;border-radius:12px;padding:1.5rem;margin-bottom:1.5rem}input,button{padding:.6rem 1rem;margin:.25rem;border-radius:8px;border:1px solid #334155}button{background:#2563eb;color:#fff;cursor:pointer;border:none}.chapter-card{display:flex;justify-content:space-between;align-items:center;padding:1rem;background:#0f172a;border-radius:8px;margin:.5rem 0}
