:root{--bg:#fff7ed;--bg2:#ffedd5;--card:#fff;--text:#3b2a1f;--muted:#8a6f5c;--pri:#f97316;--pri2:#ef4444;--ok:#16a34a;--okbg:#dcfce7;--bad:#dc2626;--badbg:#fee2e2;--line:#fed7aa;--hint:#fef9c3;--sh:0 10px 30px rgba(194,65,12,.15)}
.dark{--bg:#1c1410;--bg2:#2a1d15;--card:#2d211a;--text:#fdebd8;--muted:#c4a68f;--line:#4a3426;--okbg:#14532d;--badbg:#7f1d1d;--ok:#4ade80;--bad:#f87171;--hint:#3f3416;--sh:0 10px 30px rgba(0,0,0,.4)}
*{box-sizing:border-box}html{background:#fff7ed}html:has(body.dark){background:#1c1410}
body{margin:0;font-family:Nunito,system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;background:radial-gradient(circle at 10% 0%,var(--bg2),var(--bg) 700px) no-repeat,var(--bg);color:var(--text);min-height:100vh}
.zh{font-family:"Noto Sans SC","PingFang SC","Microsoft YaHei","Hiragino Sans GB",sans-serif}
header{display:flex;align-items:center;justify-content:space-between;padding:14px 18px;max-width:820px;margin:auto;gap:8px}
h1{font-size:1.3rem;margin:0;font-weight:900}h1 span{color:var(--pri)}
.btn{border:0;border-radius:14px;padding:10px 16px;font:inherit;font-weight:800;cursor:pointer;background:var(--card);color:var(--text);box-shadow:var(--sh);transition:transform .1s}
.btn:active{transform:scale(.96)}.btn.pri{background:linear-gradient(135deg,var(--pri),var(--pri2));color:#fff}
.btn:disabled{opacity:.4;cursor:not-allowed}
main{max-width:820px;margin:auto;padding:0 14px 40px}
.card{background:var(--card);border-radius:24px;box-shadow:var(--sh);padding:22px;margin-bottom:16px}
.chips{display:flex;flex-wrap:wrap;gap:8px;margin:8px 0 14px}
.chip{border:2px solid var(--line);background:transparent;color:var(--text);border-radius:999px;padding:7px 13px;font:inherit;font-weight:700;cursor:pointer}
.chip.on{background:var(--pri);border-color:var(--pri);color:#fff}
.tabs{display:flex;gap:6px;background:var(--bg2);padding:5px;border-radius:16px;margin-bottom:14px;overflow-x:auto}
.tab{flex:1;border:0;background:transparent;color:var(--muted);font:inherit;font-weight:800;padding:9px 10px;border-radius:12px;cursor:pointer;white-space:nowrap}
.tab.on{background:var(--card);color:var(--pri);box-shadow:var(--sh)}
label.t{font-weight:900;color:var(--muted);font-size:.8rem;text-transform:uppercase;letter-spacing:.05em}
.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;text-align:center;font-size:.85rem}
.stats b{display:block;font-size:1.4rem;color:var(--pri)}
.grid>*{min-width:0}.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(180px,1fr));gap:12px}
.lv{position:relative;text-align:left;border:2px solid var(--line);background:var(--card);color:var(--text);border-radius:18px;padding:14px;font:inherit;cursor:pointer;transition:.15s}
.lv:hover:not(.locked){border-color:var(--pri);transform:translateY(-3px)}
.lv .n{font-weight:900;color:var(--pri);font-size:.85rem}.lv .ti{font-weight:800;margin:4px 0 4px;min-height:2.6em;font-size:.95rem}
.lv .meta{display:flex;justify-content:space-between;font-size:.8rem;color:var(--muted)}
.lv .stars{letter-spacing:1px}.lv.locked{opacity:.5;cursor:not-allowed}.lv.done{border-color:#facc15}
.lv .lk{position:absolute;top:10px;right:12px}
.mini{height:6px;background:var(--line);border-radius:9px;overflow:hidden;margin-top:8px}.mini i{display:block;height:100%;background:linear-gradient(90deg,var(--pri),#facc15)}
.set{display:flex;flex-wrap:wrap;gap:14px;align-items:center;font-weight:700}
.set select{font:inherit;padding:6px 10px;border-radius:10px;border:2px solid var(--line);background:var(--card);color:var(--text)}
.sw{display:flex;align-items:center;gap:6px;cursor:pointer}.sw input{width:18px;height:18px;accent-color:var(--pri)}
.bar{height:10px;background:var(--line);border-radius:9px;overflow:hidden;margin:6px 0 14px}.bar i{display:block;height:100%;background:linear-gradient(90deg,var(--pri),#facc15);transition:width .3s}
.top{display:flex;justify-content:space-between;align-items:center;font-weight:800;gap:8px;flex-wrap:wrap}
.tag{display:inline-block;font-size:.8rem;background:var(--bg2);border-radius:999px;padding:4px 10px;color:var(--muted)}
.prompt{color:var(--muted);font-weight:700;margin:14px 0 4px}
.qrow{display:flex;align-items:center;gap:12px;flex-wrap:wrap}
.big{font-size:2.4rem;font-weight:700;line-height:1.35;word-break:break-word}.big.vi{font-family:inherit;font-weight:900;font-size:1.7rem}
.big.long{font-size:1.7rem}
.py{color:var(--pri);font-size:1.1rem;min-height:1.5em}
.tools{display:flex;gap:8px}
.opts{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-top:14px}
.opt{text-align:left;border:2px solid var(--line);background:var(--card);color:var(--text);border-radius:16px;padding:13px;font:inherit;font-size:1.05rem;font-weight:700;cursor:pointer;display:flex;gap:10px;align-items:center;transition:.15s}
.opt:hover:not(:disabled){border-color:var(--pri);transform:translateY(-2px)}
.opt .k{flex:none;width:26px;height:26px;border-radius:8px;background:var(--bg2);display:grid;place-items:center;font-size:.85rem;color:var(--muted)}
.opt.ok{background:var(--okbg);border-color:var(--ok)}.opt.bad{background:var(--badbg);border-color:var(--bad);animation:shake .35s}
.opt:disabled{cursor:default}
@keyframes shake{25%{transform:translateX(-5px)}75%{transform:translateX(5px)}}
.hintbox{margin-top:12px;background:var(--hint);border-radius:14px;padding:10px 14px;font-weight:700;animation:pop .25s}
.fb{margin-top:14px;border-radius:16px;padding:14px;font-weight:700;display:none;position:relative;overflow:hidden}.fb.show{display:block;animation:pop .25s}
.fb.ok{background:var(--okbg)}.fb.bad{background:var(--badbg)}
.cd{position:absolute;left:0;bottom:0;height:5px;background:var(--ok);width:100%}
.cdtxt{font-size:.8rem;color:var(--muted);margin-top:6px}
@keyframes pop{from{transform:scale(.96);opacity:0}}
@keyframes drain{from{width:100%}to{width:0}}
.row{display:flex;gap:10px;justify-content:space-between;align-items:center;margin-top:14px;flex-wrap:wrap}
.toast{position:fixed;left:50%;top:18px;transform:translateX(-50%) translateY(-140px);background:linear-gradient(135deg,#facc15,var(--pri));color:#fff;font-weight:900;padding:12px 20px;border-radius:999px;box-shadow:var(--sh);transition:.35s;z-index:9;text-align:center;max-width:90vw}
.toast.show{transform:translateX(-50%)}
canvas#cf{position:fixed;inset:0;pointer-events:none;z-index:8}
.rev{border-left:4px solid var(--bad);padding:8px 12px;margin:8px 0;background:var(--bg2);border-radius:10px}
.hint{color:var(--muted);font-size:.85rem;text-align:center}
.hidden{display:none!important}
.fbar{display:flex;gap:8px;flex-wrap:wrap;align-items:center;margin:4px 0 10px}
.fbar input{flex:1 1 180px;font:inherit;padding:9px 12px;border-radius:12px;border:2px solid var(--line);background:var(--card);color:var(--text)}
.fchip{border:0;background:var(--bg2);color:var(--muted);font:inherit;font-weight:800;font-size:.85rem;padding:6px 10px;border-radius:10px;cursor:pointer}.fchip.on{background:var(--pri);color:#fff}
details.grp{border:2px solid var(--line);border-radius:16px;margin:10px 0;overflow:hidden}
details.grp>summary{cursor:pointer;list-style:none;padding:12px 14px;font-weight:900;display:flex;justify-content:space-between;gap:8px;background:var(--bg2)}
details.grp>summary::-webkit-details-marker{display:none}
details.grp>summary:after{content:"▸";transition:.2s}details.grp[open]>summary:after{transform:rotate(90deg)}
details.grp .grid{padding:12px}
.lv .st{font-size:.78rem;font-weight:800;margin-top:6px}.lv .st.no{color:var(--muted)}.lv .st.yes{color:var(--ok)}
.lv .ws{font-size:.8rem;color:var(--muted);margin-bottom:4px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.lv.done{border-color:#86efac}.lv.kind-G .n:after{content:" · Ngữ pháp";color:#a855f7}
@media(max-width:560px){.tabs{flex-wrap:wrap}.tab{flex:1 1 45%}.opts{grid-template-columns:1fr}.big{font-size:2rem}.big.long{font-size:1.4rem}.big.vi{font-size:1.4rem}h1{font-size:1.05rem}.card{padding:16px}.grid{grid-template-columns:1fr 1fr;gap:8px}.lv{padding:11px}.stats{grid-template-columns:repeat(2,1fr)}header .btn{padding:8px 11px}}