:root{color:#0f172a;background:#f8fafc;font-family:Inter,PingFang SC,Hiragino Sans GB,Microsoft Yahei,system-ui,-apple-system,sans-serif;font-weight:400;line-height:1.5}*{box-sizing:border-box}body{margin:0}code{background:#e2e8f0;border-radius:6px;padding:2px 6px}.app-shell{max-width:1024px;margin:0 auto;padding:20px 16px 28px}.hero{margin-bottom:16px}.badge{color:#3730a3;background:#eef2ff;border-radius:999px;margin:0 0 10px;padding:4px 10px;font-size:12px;font-weight:700;display:inline-block}.hero h1{margin:0 0 8px;font-size:clamp(24px,4vw,34px)}.subtitle{color:#475569;margin:0}.toolbar{flex-wrap:wrap;align-items:center;gap:8px;margin-bottom:12px;display:flex}.toolbar button,.card button,.tab{cursor:pointer;background:#fff;border:1px solid #cbd5e1;border-radius:10px;padding:8px 12px;font-size:14px}.toolbar button:hover,.card button:hover,.tab:hover{border-color:#3b82f6}.tab.active{color:#1d4ed8;background:#eff6ff;border-color:#3b82f6}.level-filter{align-items:center;gap:6px;font-size:14px;display:inline-flex}.level-filter select{border:1px solid #cbd5e1;border-radius:8px;padding:6px 8px;font-size:14px}.tabs{gap:8px;margin-bottom:16px;display:flex}.message{background:#f1f5f9;border-radius:10px;margin:16px 0;padding:12px}.message.error{color:#b91c1c;background:#fee2e2}.content{min-height:220px}.grid{grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:12px;display:grid}.card{background:#fff;border:1px solid #e2e8f0;border-radius:12px;flex-direction:column;gap:10px;padding:14px;display:flex}.story-card{padding:0;overflow:hidden}.cover{aspect-ratio:4/3;object-fit:cover;background:#f1f5f9;width:100%}.cover-placeholder{color:#64748b;place-items:center;display:grid}.card-body{flex-direction:column;gap:10px;padding:14px;display:flex}.card h3{margin:0;font-size:20px}.meta{color:#64748b;margin:0;font-size:14px}.example{color:#334155;font-style:italic}.pinyin{color:#475569;font-size:14px}.empty{color:#64748b}.player{background:#e0f2fe;border-radius:12px;margin-top:18px;padding:12px}.player p{margin:0 0 6px;font-weight:600}.player audio{width:100%}@media (width<=640px){.app-shell{padding:16px 12px 20px}.tabs{overflow-x:auto}}