:root{
  --bg:#0a0f1e;--bg2:#0e1529;--card:#131c35;--card2:#1a2547;--line:rgba(255,255,255,.08);
  --text:#e9edfa;--muted:#8e9abb;--violet:#7c5cff;--cyan:#22d3ee;--lime:#a3e635;--rose:#fb7185;--amber:#fbbf24;
  --grad:linear-gradient(135deg,#7c5cff,#22d3ee);--r:18px;
}
*{box-sizing:border-box}
html,body{margin:0;min-height:100%}
body{background:var(--bg);color:var(--text);font:15px/1.55 Inter,system-ui,sans-serif;-webkit-font-smoothing:antialiased;
  background-image:radial-gradient(900px 500px at 85% -10%,rgba(124,92,255,.22),transparent 60%),radial-gradient(700px 420px at -10% 20%,rgba(34,211,238,.13),transparent 60%);background-attachment:fixed}
h1,h2,h3,.brand{font-family:Outfit,Inter,sans-serif;letter-spacing:-.01em;margin:0}
h1{font-size:clamp(26px,4vw,36px);font-weight:800}h2{font-size:20px}h3{font-size:16px}
a{color:var(--cyan);text-decoration:none}
p{margin:0}
sub,sup{font-size:.72em;line-height:0}
.boot{display:grid;place-items:center;height:100vh;font-size:48px;animation:bob 1.2s ease-in-out infinite}
@keyframes bob{50%{transform:translateY(-10px)}}
.muted{color:var(--muted)}.small{font-size:13px}.grad{background:var(--grad);-webkit-background-clip:text;background-clip:text;color:transparent}
.row{display:flex;gap:12px;align-items:center;flex-wrap:wrap}.between{justify-content:space-between}.grow{flex:1}
.stack>*+*{margin-top:16px}

/* layout */
.top{position:sticky;top:0;z-index:20;background:rgba(10,15,30,.82);backdrop-filter:blur(14px);border-bottom:1px solid var(--line)}
.top .in{max-width:1080px;margin:auto;padding:12px 16px;display:flex;align-items:center;gap:18px}
.brand{font-weight:800;font-size:20px;display:flex;align-items:center;gap:8px;color:var(--text)}
.brand i{display:grid;place-items:center;width:32px;height:32px;border-radius:10px;background:var(--grad);font-style:normal;font-size:14px;color:#fff}
.nav{display:flex;gap:4px;margin-left:auto}
.nav a{color:var(--muted);padding:8px 14px;border-radius:12px;font-weight:600;font-size:14px;display:flex;gap:6px;align-items:center}
.nav a:hover{color:var(--text);background:var(--line)}.nav a.on{color:#fff;background:rgba(124,92,255,.22)}
.chip{display:inline-flex;align-items:center;gap:5px;padding:4px 10px;border-radius:99px;font-size:12px;font-weight:700;background:var(--line);white-space:nowrap}
.chip.fire{background:rgba(251,191,36,.15);color:var(--amber)}.chip.ok{background:rgba(163,230,53,.14);color:var(--lime)}
.chip.bad{background:rgba(251,113,133,.15);color:var(--rose)}.chip.v{background:rgba(124,92,255,.2);color:#b9a8ff}
main{max-width:1080px;margin:auto;padding:24px 16px 110px}
@media(max-width:760px){
  .top{backdrop-filter:none;background:#0a0f1e}
  .nav{position:fixed;left:0;right:0;bottom:0;margin:0;background:rgba(14,21,41,.96);backdrop-filter:blur(14px);border-top:1px solid var(--line);justify-content:space-around;padding:6px 4px calc(6px + env(safe-area-inset-bottom));z-index:30}
  .nav a{flex-direction:column;gap:0;font-size:11px;padding:6px 8px}.nav a span{font-size:19px}
  .top .chip.lv{margin-left:auto}
}

/* cards & grid */
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--r);padding:20px}
.card.glow{background:linear-gradient(160deg,rgba(124,92,255,.22),rgba(34,211,238,.08) 60%),var(--card)}
.grid{display:grid;gap:14px}.g4{grid-template-columns:repeat(4,1fr)}.g3{grid-template-columns:repeat(3,1fr)}.g2{grid-template-columns:repeat(2,1fr)}
@media(max-width:900px){.g4{grid-template-columns:repeat(2,1fr)}.g3{grid-template-columns:repeat(2,1fr)}}
@media(max-width:560px){.g3,.g2{grid-template-columns:1fr}}
.stat b{display:block;font:800 28px Outfit,sans-serif}.stat span{color:var(--muted);font-size:13px}
.bar{height:10px;border-radius:99px;background:rgba(255,255,255,.08);overflow:hidden}
.bar>i{display:block;height:100%;border-radius:99px;background:var(--grad);transition:width .6s cubic-bezier(.2,.8,.2,1)}
.bar.lime>i{background:linear-gradient(90deg,#65d46e,#a3e635)}
.el{width:78px;height:86px;border-radius:16px;background:var(--grad);display:flex;flex-direction:column;justify-content:center;align-items:center;color:#fff;flex:none;box-shadow:0 10px 30px rgba(124,92,255,.35);position:relative}
.el small{position:absolute;top:6px;left:9px;font-size:11px;font-weight:700;opacity:.85}.el b{font:800 32px/1 Outfit,sans-serif}.el em{font-style:normal;font-size:10px;opacity:.9;margin-top:3px}
.el.big{width:130px;height:144px;border-radius:26px}.el.big b{font-size:58px}.el.big em{font-size:14px}.el.big small{font-size:15px;top:10px;left:14px}
.ring{width:74px;height:74px;flex:none;transform:rotate(-90deg)}.ring circle{fill:none;stroke-width:8;stroke:rgba(255,255,255,.08)}.ring .p{stroke:var(--lime);stroke-linecap:round;transition:stroke-dashoffset .8s}
.action{display:flex;gap:14px;align-items:center;cursor:pointer;transition:transform .15s,border-color .15s;color:var(--text)}
.action:hover{transform:translateY(-3px);border-color:rgba(124,92,255,.6)}
.action .ic{font-size:30px;width:54px;height:54px;border-radius:16px;display:grid;place-items:center;background:var(--card2);flex:none}

/* buttons & forms */
.btn{appearance:none;border:0;cursor:pointer;font:700 15px Inter,sans-serif;color:#fff;background:var(--grad);padding:12px 20px;border-radius:14px;transition:transform .12s,filter .12s;display:inline-flex;gap:8px;align-items:center;justify-content:center}
.btn:hover{filter:brightness(1.1)}.btn:active{transform:scale(.97)}.btn:disabled{opacity:.5;cursor:default}
.btn.ghost{background:var(--card2);border:1px solid var(--line)}.btn.sm{padding:7px 12px;font-size:13px;border-radius:10px}.btn.danger{background:rgba(251,113,133,.18);color:var(--rose)}
.btn.block{width:100%}
label{display:block;font-size:13px;font-weight:600;color:var(--muted);margin-bottom:6px}
input,select,textarea{width:100%;background:var(--bg2);border:1px solid var(--line);color:var(--text);padding:12px 14px;border-radius:12px;font:inherit;outline:none}
input:focus,select:focus,textarea:focus{border-color:var(--violet);box-shadow:0 0 0 3px rgba(124,92,255,.25)}
textarea{min-height:110px;resize:vertical}
.field+.field{margin-top:14px}
.err{color:var(--rose);font-size:14px;min-height:20px;margin-top:10px}

/* auth */
.auth{min-height:100vh;display:grid;grid-template-columns:1.1fr 1fr;max-width:1080px;margin:auto;gap:40px;align-items:center;padding:24px 16px}
.auth .pitch h1{font-size:clamp(32px,5vw,52px);line-height:1.08}
.auth .pitch li{margin:10px 0;list-style:none;display:flex;gap:10px}.auth .pitch ul{padding:0;margin:22px 0 0}
@media(max-width:820px){.auth{grid-template-columns:1fr;gap:20px;align-content:center}.auth .pitch ul{display:none}}
.tabs{display:flex;gap:6px;background:var(--bg2);padding:5px;border-radius:14px;margin-bottom:18px}
.tabs a,.tabs button{flex:1;text-align:center;padding:9px 12px;border-radius:10px;color:var(--muted);font-weight:700;font-size:14px;border:0;background:none;cursor:pointer;white-space:nowrap}
.tabs .on{background:var(--card2);color:#fff}
.tabs.scroll{overflow-x:auto}.tabs.scroll a{flex:none}

/* chapters */
.sec{margin:26px 0 12px;color:var(--muted);font-size:12px;font-weight:700;letter-spacing:.12em;text-transform:uppercase}
.ch{cursor:pointer;display:flex;flex-direction:column;gap:12px;transition:transform .15s,border-color .15s;color:var(--text)}
.ch:hover{transform:translateY(-3px);border-color:rgba(34,211,238,.5)}
.ch .n{font:800 13px Outfit;color:var(--cyan)}
.ch.done{border-color:rgba(163,230,53,.4)}

/* practice */
.pwrap{max-width:760px;margin:auto}
.dots{display:flex;gap:5px;flex:1}.dots i{height:8px;flex:1;border-radius:99px;background:rgba(255,255,255,.1)}
.dots i.ok{background:var(--lime)}.dots i.no{background:var(--rose)}.dots i.cur{background:var(--violet)}
.stem{font-size:17px;line-height:1.65;margin:16px 0 20px}
.qimg{max-width:100%;border-radius:12px;margin-bottom:16px;background:#fff}
.opt{display:flex;gap:14px;align-items:center;width:100%;text-align:left;background:var(--card2);border:2px solid transparent;color:var(--text);padding:14px 16px;border-radius:14px;font:inherit;font-size:16px;cursor:pointer;margin-top:10px;transition:border-color .12s,transform .12s}
.opt:hover:not(:disabled){border-color:var(--violet);transform:translateX(3px)}
.opt k{flex:none;width:32px;height:32px;border-radius:10px;display:grid;place-items:center;font-weight:800;background:rgba(255,255,255,.08)}
.opt.right{border-color:var(--lime);background:rgba(163,230,53,.1)}.opt.right k{background:var(--lime);color:#14210a}
.opt.wrong{border-color:var(--rose);background:rgba(251,113,133,.1);animation:shake .35s}.opt.wrong k{background:var(--rose);color:#2a0a10}
.opt:disabled{cursor:default}
@keyframes shake{25%{transform:translateX(-6px)}75%{transform:translateX(6px)}}
.explain{margin-top:18px;padding:16px 18px;border-radius:14px;background:var(--bg2);border-left:4px solid var(--cyan);animation:rise .3s}
.explain.good{border-color:var(--lime)}.explain.bad{border-color:var(--rose)}
@keyframes rise{from{opacity:0;transform:translateY(8px)}}
.xp-pop{font-weight:800;color:var(--lime)}
.marks{display:flex;gap:8px;flex-wrap:wrap;margin-top:12px}
.notes h3{margin:20px 0 8px;color:var(--cyan)}.notes ul{margin:0;padding-left:20px}.notes li{margin:6px 0}

/* table */
.tw{overflow-x:auto}table{width:100%;border-collapse:collapse;font-size:14px}
th{text-align:left;color:var(--muted);font-size:12px;text-transform:uppercase;letter-spacing:.06em;padding:8px 10px;white-space:nowrap}
td{padding:10px;border-top:1px solid var(--line);vertical-align:middle}
tr.me td{background:rgba(124,92,255,.14)}
code{background:var(--bg2);padding:3px 8px;border-radius:8px;font-size:13px;user-select:all}

/* toast, modal, watermark, confetti */
#toasts{position:fixed;top:16px;left:50%;transform:translateX(-50%);z-index:100;display:flex;flex-direction:column;gap:8px;align-items:center;pointer-events:none;width:min(92vw,440px)}
.toast{background:#1d2850;border:1px solid var(--line);padding:12px 18px;border-radius:14px;font-weight:600;box-shadow:0 10px 40px rgba(0,0,0,.5);animation:rise .25s}
.toast.bad{border-color:var(--rose)}.toast.good{border-color:var(--lime)}
#modal{position:fixed;inset:0;z-index:90;background:rgba(5,8,18,.8);backdrop-filter:blur(6px);display:grid;place-items:center;padding:16px}
#modal[hidden]{display:none}
#modal .box{max-width:460px;width:100%;text-align:center;animation:pop .4s cubic-bezier(.2,1.4,.4,1)}
#modal .box.wide{max-width:720px;text-align:left;max-height:90vh;overflow:auto}
@keyframes pop{from{transform:scale(.7);opacity:0}}
#wm{position:fixed;inset:0;z-index:15;pointer-events:none;opacity:.07;background-repeat:repeat}
.confetti{position:fixed;top:-20px;z-index:95;font-size:22px;pointer-events:none;animation:fall linear forwards}
@keyframes fall{to{transform:translateY(110vh) rotate(720deg)}}
body.protect main{-webkit-user-select:none;user-select:none}
body.protect input,body.protect textarea{-webkit-user-select:text;user-select:text}
@media print{body{display:none!important}}