:root{--ink:#e2e8f0;--muted:#94a3b8;--bg-deep:#0b1220;--line:#94a3b838;--elev:0 18px 50px #00000059;font-synthesis:none;text-rendering:optimizelegibility;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;font-family:Segoe UI,system-ui,-apple-system,Roboto,PingFang SC,Microsoft YaHei,sans-serif;line-height:1.5}*,:before,:after{box-sizing:border-box}html,body{background:var(--bg-deep);height:100%;color:var(--ink);margin:0}#root{min-height:100%}button:focus-visible,.tile:focus-visible,.hub-card:focus-visible{outline-offset:2px;outline:2px solid #a5b4fc}.app-root{min-height:100svh;color:var(--ink);background:radial-gradient(1200px 600px at 10% -10%, #6366f12e, transparent), radial-gradient(900px 500px at 100% 0%, #ec48991f, transparent), var(--bg-deep);flex-direction:column;display:flex}.app-header{border-bottom:1px solid var(--line);-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);z-index:10;background:#0f172a8c;justify-content:space-between;align-items:center;gap:12px;padding:14px 18px;display:flex;position:sticky;top:0}.brand{letter-spacing:.02em;align-items:center;gap:10px;font-weight:700;display:flex}.brand-mark{background:linear-gradient(135deg,#6366f1,#ec4899);border-radius:10px;place-items:center;width:36px;height:36px;font-size:18px;display:grid}.xp-pill{border:1px solid var(--line);color:var(--muted);border-radius:999px;padding:6px 12px;font-size:13px}.main-pad{box-sizing:border-box;flex:1;width:min(920px,100%);margin:0 auto;padding:20px 16px 32px}.hero-card{text-align:left;border:1px solid var(--line);box-shadow:var(--elev);background:linear-gradient(145deg,#1e293beb,#0f172abf);border-radius:20px;padding:28px 24px}.hero-card h1{color:var(--ink);margin:0 0 10px;font-size:clamp(26px,4vw,34px);line-height:1.15}.hero-card p{color:var(--muted);max-width:52ch;margin:0 0 20px}.grid-grades{grid-template-columns:repeat(auto-fill,minmax(160px,1fr));gap:12px;margin-top:20px;display:grid}.tile{border:1px solid var(--line);cursor:pointer;text-align:left;color:inherit;font:inherit;background:#1e293b8c;border-radius:16px;padding:16px 14px;transition:transform .15s,border-color .15s,background .15s}.tile:hover{background:#1e293bd9;border-color:#6366f173;transform:translateY(-2px)}.tile:active{transform:translateY(0)}.tile h3{color:var(--ink);margin:0 0 6px;font-size:17px}.tile small{color:var(--muted);line-height:1.35}.hub-grid{grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:14px;margin-top:18px;display:grid}.hub-card{border:1px solid var(--line);cursor:pointer;text-align:left;color:inherit;font:inherit;background:#0f172aa6;border-radius:18px;padding:18px 16px;transition:transform .15s,border-color .15s}.hub-card:hover{border-color:#ec489966;transform:translateY(-2px)}.hub-card .icon{margin-bottom:8px;font-size:28px}.hub-card h3{margin:0 0 6px;font-size:18px}.row{flex-wrap:wrap;align-items:center;gap:10px;display:flex}.btn{border:1px solid var(--line);color:var(--ink);cursor:pointer;font:inherit;background:#6366f12e;border-radius:12px;padding:10px 16px;font-weight:600}.btn:hover{background:#6366f147}.btn-ghost{background:0 0}.btn-primary{background:linear-gradient(135deg,#6366f1,#8b5cf6);border-color:#0000}.btn-primary:hover{filter:brightness(1.06)}.panel{border:1px solid var(--line);text-align:left;background:#0f172a8c;border-radius:16px;margin-top:16px;padding:18px}.flashcard{background:#02061759;border:1px dashed #94a3b859;border-radius:16px;place-items:center;min-height:160px;padding:20px;display:grid}.flashcard .en{letter-spacing:.02em;font-size:clamp(28px,5vw,40px);font-weight:800}.flashcard .zh{color:var(--muted);margin-top:10px;font-size:18px}.mc-grid{gap:10px;margin-top:14px;display:grid}.mc-opt{text-align:left;border:1px solid var(--line);cursor:pointer;color:inherit;font:inherit;background:#0f172a73;border-radius:12px;padding:12px 14px}.mc-opt:hover{border-color:#6366f180}.mc-opt.correct{background:#22c55e1f;border-color:#22c55ea6}.mc-opt.wrong{background:#f871711a;border-color:#f87171a6}.sentence{color:var(--ink);font-size:18px;line-height:1.6}.blank{text-align:center;color:#a5b4fc;border-bottom:2px solid #6366f1a6;min-width:3.2ch;margin:0 4px;padding:0 6px;display:inline-block}.stages{flex-direction:column;gap:10px;margin-top:12px;display:flex}.stage-row{border:1px solid var(--line);background:#0f172a73;border-radius:14px;justify-content:space-between;align-items:center;gap:12px;padding:12px 14px;display:flex}.stage-row.locked{opacity:.55}.stars{letter-spacing:2px;color:#fbbf24}.tag{border:1px solid var(--line);color:var(--muted);border-radius:999px;padding:4px 8px;font-size:12px}.toast{color:var(--ink);background:#6366f126;border:1px solid #6366f159;border-radius:12px;margin-top:10px;padding:10px 12px}.muted{color:var(--muted);font-size:14px}.badge-list{flex-wrap:wrap;gap:8px;margin-top:10px;display:flex}.badge{border:1px solid var(--line);color:var(--muted);border-radius:999px;padding:8px 10px;font-size:13px}.badge.on{color:#bbf7d0;background:#22c55e1a;border-color:#22c55e73}