:root{
  --page:#EEF2EE; --surface:#FFFFFF; --surface2:#F1F5F1; --ink:#13241F; --muted:#5B6C66; --line:#D9E1DB;
  --board:#103B32; --board2:#185246; --chalk:#F4F7EF; --accent:#E3902A; --accent-ink:#2A1A05; --accent-soft:#FBEBD3;
  --good:#23855A; --good-soft:#DDF1E6; --bad:#B8430F; --bad-soft:#F9E3D8;
  --display:"Bricolage Grotesque","Segoe UI",system-ui,sans-serif;
  --body:"Hind","Segoe UI",system-ui,sans-serif;
  --r:16px;
}
@media (prefers-color-scheme: dark){:root{
  color-scheme:dark;--page:#0A1311;--surface:#121E1B;--surface2:#182723;--ink:#E6EEE9;--muted:#95A7A0;--line:#263A34;
  --board:#0E3A31;--board2:#1A564A;--accent:#F0A445;--accent-soft:#3A2A14;--good:#4CC08A;--good-soft:#15352A;--bad:#F08A5D;--bad-soft:#3A2016;}}
*{box-sizing:border-box}
[hidden]{display:none!important}
html,body{margin:0}
body{background:var(--page);color:var(--ink);font-family:var(--body);font-size:15.5px;line-height:1.5;-webkit-font-smoothing:antialiased}
button,input,textarea,select{font:inherit;color:inherit}
button{cursor:pointer}
a{color:inherit}
img{max-width:100%}
:focus-visible{outline:2px solid var(--accent);outline-offset:2px}

/* layout */
.shell{display:flex;min-height:100vh}
.main{flex:1;min-width:0;max-width:880px;margin:0 auto;padding-bottom:calc(84px + env(safe-area-inset-bottom,0px));outline:none}
.side{display:none}
.tabs{position:fixed;left:0;right:0;bottom:0;display:grid;grid-template-columns:repeat(5,1fr);background:var(--surface);border-top:1px solid var(--line);padding:6px 4px calc(8px + env(safe-area-inset-bottom,0px));z-index:20}
.tabs a,.side a{display:flex;flex-direction:column;align-items:center;gap:2px;font-size:11.5px;color:var(--muted);padding:6px 0;font-weight:500;text-decoration:none}
.tabs svg,.side svg{width:22px;height:22px}
.tabs a[aria-current="page"]{color:var(--board)}
@media (prefers-color-scheme: dark){.tabs a[aria-current="page"],.side a[aria-current="page"]{color:var(--accent)}}
@media (min-width:900px){
  .tabs{display:none}
  .main{padding-bottom:40px}
  .side{display:flex;flex-direction:column;gap:4px;width:220px;flex:none;position:sticky;top:0;height:100vh;padding:22px 14px;background:var(--surface);border-right:1px solid var(--line)}
  .side .brand{margin:0 8px 18px;color:var(--ink)}
  .side a{flex-direction:row;gap:12px;font-size:15px;padding:10px 12px;border-radius:12px}
  .side a[aria-current="page"]{background:var(--surface2);color:var(--board);font-weight:600}
}

/* common */
.top{background:var(--board);color:var(--chalk);padding:20px 18px 22px;position:relative}
@media (min-width:900px){.top{border-radius:0 0 22px 22px}}
.top .row{display:flex;justify-content:space-between;align-items:center;gap:10px}
.top h1{font-family:var(--display);font-weight:700;font-size:25px;margin:8px 0 0;line-height:1.15;text-wrap:balance}
.top small{opacity:.78;font-size:13.5px;display:block;margin-top:4px}
.back{background:rgba(255,255,255,.12);border:0;border-radius:12px;width:38px;height:38px;display:grid;place-items:center;color:var(--chalk);text-decoration:none}
.pill{display:inline-flex;align-items:center;gap:6px;border-radius:999px;padding:4px 11px;font-size:12.5px;font-weight:600;background:rgba(255,255,255,.14);color:var(--chalk);border:0;text-decoration:none}
.brand{display:flex;align-items:center;gap:9px;font-family:var(--display);font-weight:800;font-size:18px;letter-spacing:-.01em}
.mark{width:32px;height:32px;border-radius:10px;background:var(--accent);color:var(--accent-ink);display:grid;place-items:center;font-size:16px;font-weight:800;flex:none}
.body{padding:18px 16px 26px;display:flex;flex-direction:column;gap:18px}
.sec-h{display:flex;justify-content:space-between;align-items:baseline;gap:10px}
.sec-h h2,.h2{font-family:var(--display);font-size:18px;margin:0;font-weight:700}
.sec-h a{color:var(--accent);font-weight:600;font-size:14px;text-decoration:none}
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:14px}
.card.soft{background:var(--surface2);border-color:transparent}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;border:0;border-radius:14px;padding:13px 16px;font-weight:600;background:var(--board);color:#fff;font-size:15px;text-decoration:none;width:100%}
.btn.alt{background:var(--accent);color:var(--accent-ink)}
.btn.ghost{background:transparent;border:1.5px solid var(--line);color:var(--ink)}
.btn.small{width:auto;padding:9px 14px;font-size:14px;border-radius:12px}
.btn:disabled{opacity:.45;cursor:not-allowed}
.muted{color:var(--muted)}
.tiny{font-size:13px}
.row2{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.grid-subj{display:grid;grid-template-columns:repeat(auto-fill,minmax(104px,1fr));gap:10px}
label.lbl{font-weight:600;font-size:14px;display:block;margin-bottom:6px}
.field{width:100%;border:1.5px solid var(--line);background:var(--surface);border-radius:12px;padding:12px}
textarea.field{min-height:96px;resize:vertical}
.choice{border:1.5px solid var(--line);background:var(--surface);border-radius:14px;padding:12px;text-align:left;font-weight:600;width:100%}
.choice small{display:block;font-weight:400;color:var(--muted);font-size:12.5px}
.choice[aria-pressed="true"]{border-color:var(--board);background:var(--good-soft)}
.chips{display:flex;flex-wrap:wrap;gap:8px}
.chip{border:1.5px solid var(--line);background:var(--surface);border-radius:999px;padding:7px 13px;font-weight:600;font-size:14px}
.chip[aria-pressed="true"]{background:var(--board);color:#fff;border-color:var(--board)}
.seg{display:flex;background:var(--surface2);border-radius:12px;padding:4px;gap:4px}
.seg button{flex:1;border:0;background:none;border-radius:9px;padding:8px 4px;font-weight:600;font-size:14px;color:var(--muted)}
.seg button[aria-pressed="true"]{background:var(--surface);color:var(--ink);box-shadow:0 1px 3px rgba(0,0,0,.12)}
.list{display:flex;flex-direction:column}
.item{display:flex;gap:12px;align-items:center;padding:13px 4px;border-bottom:1px solid var(--line);text-decoration:none;color:inherit;background:none;border-left:0;border-right:0;border-top:0;width:100%;text-align:left}
.item:last-child{border-bottom:0}
.item .num{width:36px;height:36px;flex:none;border-radius:11px;background:var(--surface2);display:grid;place-items:center;font-weight:700;font-size:13.5px;font-variant-numeric:tabular-nums}
.item .t{flex:1;min-width:0}
.item .t b{display:block;font-weight:600;line-height:1.3}
.tag{flex:none;align-self:center;font-size:12px;font-weight:600;border-radius:999px;padding:2px 9px;white-space:nowrap}
.tag.good{background:var(--good-soft);color:var(--good)}
.tag.warn{background:var(--accent-soft);color:#A8620E}
@media (prefers-color-scheme: dark){.tag.warn{color:var(--accent)}}
.tag.lock{background:var(--surface2);color:var(--muted)}
.tag.bad{background:var(--bad-soft);color:var(--bad)}
.bar{height:6px;border-radius:9px;background:var(--line);overflow:hidden}
.bar i{display:block;height:100%;background:var(--accent);border-radius:9px}
.empty{text-align:center;padding:26px 14px;color:var(--muted)}
.toast{position:fixed;left:50%;bottom:calc(92px + env(safe-area-inset-bottom,0px));transform:translate(-50%,10px);max-width:min(92vw,460px);background:var(--ink);color:var(--surface);border-radius:14px;padding:12px 16px;font-size:14.5px;font-weight:500;opacity:0;transition:.25s;pointer-events:none;z-index:50}
.toast.show{opacity:1;transform:translate(-50%,0)}
@media (min-width:900px){.toast{bottom:28px}}
.spin{width:28px;height:28px;border-radius:50%;border:3px solid var(--line);border-top-color:var(--accent);animation:sp 1s linear infinite;margin:40px auto}
@keyframes sp{to{transform:rotate(360deg)}}

/* login */
.hero{background:var(--board);color:var(--chalk);padding:44px 22px 30px;position:relative;overflow:hidden}
@media (min-width:900px){.hero{border-radius:0 0 26px 26px}}
.hero h1{font-family:var(--display);font-size:34px;line-height:1.05;margin:26px 0 8px;font-weight:800;letter-spacing:-.02em;text-wrap:balance}
.hero p{margin:0;opacity:.82}
.boards{display:flex;flex-wrap:wrap;gap:6px;margin-top:16px}
.boards span{font-size:12px;font-weight:600;border:1px solid rgba(255,255,255,.28);border-radius:999px;padding:3px 9px}
.otp{letter-spacing:.5em;text-align:center;font-size:24px;font-weight:700}
.testmode{background:var(--accent-soft);border-radius:12px;padding:10px 12px;font-size:14px}

/* home */
.cont{display:block;background:var(--board);color:var(--chalk);border-radius:20px;padding:16px;text-decoration:none}
.cont b{font-family:var(--display);font-size:17px;display:block;margin:2px 0 10px}
.cont .bar{background:rgba(255,255,255,.2)}
.subj{border:0;background:var(--surface);border:1px solid var(--line);border-radius:16px;padding:14px 8px;display:flex;flex-direction:column;align-items:center;gap:6px;font-weight:600;font-size:13.5px;text-decoration:none;color:inherit;text-align:center}
.subj .ic{width:46px;height:46px;border-radius:13px;display:grid;place-items:center;font-family:var(--display);font-weight:800;font-size:17px;background:var(--surface2);color:var(--board)}
@media (prefers-color-scheme: dark){.subj .ic{color:var(--accent)}}
.review{background:var(--surface);border:1px solid var(--line);border-radius:16px;padding:14px;display:flex;flex-direction:column;gap:6px}
.review p{margin:0}
.stars-s{color:var(--accent);letter-spacing:1px}

/* topic flow */
.step{display:flex;gap:12px;align-items:flex-start}
.step .dot{width:30px;height:30px;border-radius:50%;flex:none;display:grid;place-items:center;font-weight:700;font-size:13px;background:var(--surface2);color:var(--muted)}
.step .dot.done{background:var(--good);color:#fff}
.step .dot.now{background:var(--accent);color:var(--accent-ink)}

/* player */
.player{background:#07191A;position:relative;aspect-ratio:16/9;width:100%;overflow:hidden}
@media (min-width:900px){.player{border-radius:0 0 18px 18px}}
.player video,.player iframe{position:absolute;inset:0;width:100%;height:100%;border:0;background:#000}
.player .noVideo{position:absolute;inset:0;display:grid;place-items:center;text-align:center;color:#D9E8E3;padding:20px}
.player .noVideo b{font-family:var(--display);font-size:18px;display:block}
.pausebox{position:absolute;inset:0;display:grid;place-items:center;background:rgba(3,15,12,.5)}
.pausebox .in{display:flex;flex-direction:column;gap:10px;align-items:center}
.v3d{position:absolute;inset:0;background:#081E19;z-index:3}
.v3d canvas{display:block;width:100%;height:100%;touch-action:none}
.v3d .tools{position:absolute;right:10px;top:10px;display:flex;flex-direction:column;gap:7px;z-index:2}
.v3d .tools button{min-width:42px;height:40px;border-radius:12px;border:0;background:rgba(255,255,255,.16);color:#fff;font-weight:700;font-size:13px;padding:0 11px}
.v3d .tools button[aria-pressed="true"]{background:var(--accent);color:var(--accent-ink)}
.v3d .tools .z{display:flex;gap:6px}
.v3d .tools .z button{font-size:20px;padding:0}
.v3d .close{position:absolute;left:10px;bottom:10px;border:0;border-radius:12px;padding:9px 13px;background:var(--accent);color:var(--accent-ink);font-weight:700;z-index:2}
.v3d .info{position:absolute;left:10px;top:10px;max-width:min(320px,60%);background:rgba(255,255,255,.94);color:#13241F;border-radius:12px;padding:8px 11px;font-size:13.5px;line-height:1.4;z-index:2}
.v3d .info b{font-family:var(--display);display:block;font-size:14.5px}
.v3d .labels{position:absolute;inset:0;pointer-events:none;z-index:1}
.v3d .lab{position:absolute;display:flex;align-items:center;gap:5px;transform:translate(-5px,-50%);pointer-events:auto;cursor:pointer;white-space:nowrap}
.v3d .lab i{width:9px;height:9px;border-radius:50%;background:var(--accent);border:2px solid #fff}
.v3d .lab span{background:rgba(255,255,255,.92);color:#13241F;font-weight:600;font-size:12.5px;border-radius:7px;padding:1px 7px}
.v3d .lab.on span{background:var(--accent);color:var(--accent-ink)}
.v3d .fsbtn{position:absolute;right:10px;bottom:10px;z-index:2;border:0;border-radius:12px;padding:9px 12px;background:rgba(255,255,255,.16);color:#fff;font-weight:700;font-size:13px}
.player:fullscreen{aspect-ratio:auto}
.player.has3d{aspect-ratio:auto;height:min(76vh,640px)}
@media (min-width:900px){.player.has3d{height:auto;aspect-ratio:16/9}}
@media (max-width:560px){.v3d .info{max-width:calc(100% - 120px);font-size:12.5px}}
.stars{display:flex;gap:4px}
.stars button{background:none;border:0;padding:2px;color:var(--line)}
.stars button.on{color:var(--accent)}
.stars svg{width:30px;height:30px;display:block}

/* notes */
.notes h3{font-family:var(--display);font-size:17px;margin:16px 0 6px}
.notes table{width:100%;border-collapse:collapse;font-variant-numeric:tabular-nums}
.notes td{border-bottom:1px solid var(--line);padding:8px 6px}
.notes td:last-child{font-weight:600}
.notes p,.notes li{max-width:68ch}

/* tests */
.qtype{font-size:12px;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.q{font-family:var(--display);font-size:18.5px;font-weight:700;line-height:1.35;margin:4px 0 0;white-space:pre-line}
.opt{display:flex;gap:10px;align-items:center;width:100%;text-align:left;border:1.5px solid var(--line);background:var(--surface);border-radius:14px;padding:12px;font-weight:500}
.opt .l{width:28px;height:28px;flex:none;border-radius:8px;background:var(--surface2);display:grid;place-items:center;font-weight:700;font-size:13px}
.opt[aria-pressed="true"]{border-color:var(--board);background:var(--good-soft)}
.opt.right{border-color:var(--good);background:var(--good-soft)}
.opt.wrong{border-color:var(--bad);background:var(--bad-soft)}
.sol{border-left:3px solid var(--good);padding:6px 0 6px 12px;white-space:pre-line}
.steps{display:flex;gap:4px}
.steps i{flex:1;height:5px;border-radius:9px;background:var(--line)}
.steps i.done{background:var(--board)}
.steps i.now{background:var(--accent)}
.score{background:var(--board);color:var(--chalk);border-radius:20px;padding:22px;text-align:center}
.score b{font-family:var(--display);font-size:54px;display:block;line-height:1;font-variant-numeric:tabular-nums}

/* doubts */
.doubt{background:var(--surface);border:1px solid var(--line);border-radius:16px;padding:14px;display:flex;flex-direction:column;gap:8px}
.doubt .ans{background:var(--surface2);border-radius:12px;padding:10px 12px;white-space:pre-line}
.doubt img{border-radius:10px;max-height:220px;object-fit:contain;align-self:flex-start}

/* me */
.stats{display:grid;grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:10px}
.stat{background:var(--surface);border:1px solid var(--line);border-radius:16px;padding:12px 14px}
.stat b{font-family:var(--display);font-size:26px;display:block;font-variant-numeric:tabular-nums;line-height:1.1}
.prow{display:grid;grid-template-columns:110px 1fr 44px;gap:10px;align-items:center;font-size:14px;font-variant-numeric:tabular-nums}
.plan{border:1.5px solid var(--line);border-radius:18px;padding:16px;display:flex;flex-direction:column;gap:8px;background:var(--surface)}
.plan.best{border-color:var(--accent);background:var(--accent-soft)}
.plan .price{font-family:var(--display);font-size:28px;font-weight:800;font-variant-numeric:tabular-nums}
.plan ul{margin:0;padding-left:18px;font-size:14.5px}
.plans{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:12px}
@media (prefers-reduced-motion: reduce){*{transition:none!important;animation:none!important}}