:root{
  --bg:#0a0c14;--bg2:#0f1322;--card:rgba(255,255,255,.045);--border:rgba(255,255,255,.09);
  --text:#e8eaf2;--muted:#9aa3b8;--acc:#7c6cff;--acc2:#2dd4bf;--pink:#f472b6;--gold:#fbbf24;
  --glass:rgba(18,22,38,.65);--shadow:0 18px 50px rgba(0,0,0,.45);--radius:16px;
}
body.light{--bg:#f4f6fb;--bg2:#eaeefb;--card:rgba(255,255,255,.75);--border:rgba(20,30,60,.1);--text:#16203a;--muted:#5b6477;--glass:rgba(255,255,255,.7);--shadow:0 14px 40px rgba(30,40,90,.12);}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:'Inter','Segoe UI',system-ui,sans-serif;background:radial-gradient(1100px 600px at 80% -10%,rgba(124,108,255,.18),transparent),radial-gradient(900px 500px at -10% 30%,rgba(45,212,191,.12),transparent),var(--bg);color:var(--text);min-height:100vh}
code{font-family:'JetBrains Mono','Fira Code',Consolas,monospace;background:rgba(124,108,255,.14);padding:2px 7px;border-radius:6px;font-size:.9em;color:var(--acc2)}
.glass{background:var(--glass);backdrop-filter:blur(14px);-webkit-backdrop-filter:blur(14px);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow)}
.grad{background:linear-gradient(90deg,var(--acc),var(--acc2),var(--pink));-webkit-background-clip:text;background-clip:text;color:transparent}

/* NAV */
.nav{position:sticky;top:12px;z-index:50;display:flex;align-items:center;gap:18px;margin:12px auto 0;max-width:1180px;padding:10px 18px;border-radius:99px}
.logo{font-weight:800;font-size:1.15rem;text-decoration:none;color:var(--text);display:flex;align-items:center;gap:8px}
.logo-mark{display:inline-grid;place-items:center;width:30px;height:30px;border-radius:9px;background:linear-gradient(135deg,var(--acc),var(--acc2));color:#fff;font-size:1rem}
.menu{display:flex;gap:4px;flex:1;justify-content:center;flex-wrap:wrap}
.menu a{color:var(--muted);text-decoration:none;padding:7px 13px;border-radius:99px;font-size:.92rem;transition:.2s}
.menu a:hover{color:var(--text);background:var(--card)}
.menu a.active{color:#fff;background:linear-gradient(135deg,var(--acc),#5a4fd6)}
.nav-right{display:flex;gap:10px;align-items:center}
.icon-btn{background:var(--card);border:1px solid var(--border);border-radius:99px;width:36px;height:36px;cursor:pointer;font-size:1rem}
.chip{display:inline-block;padding:6px 13px;border-radius:99px;background:var(--card);border:1px solid var(--border);font-size:.85rem;color:var(--muted)}
.chip.glow{color:var(--acc2);border-color:rgba(45,212,191,.4);box-shadow:0 0 22px rgba(45,212,191,.18)}

main{max-width:1180px;margin:0 auto;padding:28px 20px 60px}
.page{display:none;animation:fadeUp .45s ease}
.page.active{display:block}
@keyframes fadeUp{from{opacity:0;transform:translateY(14px)}to{opacity:1;transform:none}}
h1{font-size:clamp(2rem,4.6vw,3.4rem);line-height:1.12;letter-spacing:-.02em}
h2{font-size:clamp(1.5rem,3vw,2.2rem);margin:18px 0 8px;letter-spacing:-.01em}
.sub{color:var(--muted);max-width:640px;margin:10px 0 22px;line-height:1.65}

/* HERO */
.hero{display:grid;grid-template-columns:1.05fr 1fr;gap:34px;align-items:center;padding:46px 0 20px}
.hero-text .chip{margin-bottom:18px}
.cta-row{display:flex;gap:14px;margin:26px 0}
.btn{display:inline-block;padding:13px 26px;border-radius:12px;text-decoration:none;font-weight:600;border:1px solid var(--border);color:var(--text);cursor:pointer;font-size:.95rem;transition:.22s;background:transparent}
.btn.primary{background:linear-gradient(135deg,var(--acc),#5a4fd6);color:#fff;border:none;box-shadow:0 10px 30px rgba(124,108,255,.35)}
.btn.primary:hover{transform:translateY(-2px);box-shadow:0 16px 38px rgba(124,108,255,.5)}
.btn.ghost:hover{background:var(--card)}
.btn.small{padding:7px 14px;font-size:.82rem;border-radius:9px}
.float-chips{display:flex;gap:10px;flex-wrap:wrap}
.float-chips span{font-family:monospace;font-size:.8rem;padding:6px 12px;border-radius:9px;background:var(--card);border:1px solid var(--border);color:var(--acc2);animation:floaty 4s ease-in-out infinite}
.float-chips span:nth-child(2){animation-delay:.6s}.float-chips span:nth-child(3){animation-delay:1.2s}.float-chips span:nth-child(4){animation-delay:1.8s}.float-chips span:nth-child(5){animation-delay:2.4s}
@keyframes floaty{0%,100%{transform:translateY(0)}50%{transform:translateY(-7px)}}
.hero-visual{position:relative;height:420px;overflow:hidden;cursor:grab}
.hero-visual:active{cursor:grabbing}
#hero3d{width:100%;height:100%;display:block}
.hero-hint{position:absolute;bottom:12px;left:0;right:0;text-align:center;color:var(--muted);font-size:.8rem;pointer-events:none}
.feature-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:16px;margin-top:34px}
.feature{padding:22px;border-radius:var(--radius);background:var(--card);border:1px solid var(--border);transition:.25s}
.feature:hover{transform:translateY(-4px);border-color:rgba(124,108,255,.45)}
.feature .ic{font-size:1.6rem}
.feature h3{margin:10px 0 6px;font-size:1.02rem}
.feature p{color:var(--muted);font-size:.88rem;line-height:1.55}

/* ROADMAP */
.roadmap{display:flex;flex-direction:column;gap:16px;margin-top:10px}
.level{padding:22px;display:grid;grid-template-columns:64px 1fr;gap:18px;position:relative;overflow:hidden}
.level.locked{opacity:.55}
.lvl-badge{width:52px;height:52px;border-radius:14px;display:grid;place-items:center;font-weight:800;font-size:1.2rem;color:#fff;background:linear-gradient(135deg,var(--acc),var(--acc2))}
.level.locked .lvl-badge{background:var(--card);color:var(--muted);border:1px solid var(--border)}
.level h3{font-size:1.12rem;margin-bottom:6px}
.topic-chips{display:flex;flex-wrap:wrap;gap:8px;margin:10px 0}
.topic-chips span{font-size:.78rem;padding:5px 11px;border-radius:99px;background:var(--card);border:1px solid var(--border);color:var(--muted)}
.topic-chips span.done{color:var(--acc2);border-color:rgba(45,212,191,.5)}
.pbar{height:8px;border-radius:99px;background:var(--card);overflow:hidden;margin-top:6px}
.pbar i{display:block;height:100%;border-radius:99px;background:linear-gradient(90deg,var(--acc),var(--acc2));transition:width .8s cubic-bezier(.2,.8,.2,1)}
.lock-tag{position:absolute;top:16px;right:18px;font-size:.75rem;color:var(--muted)}

/* LESSONS */
.lessons-layout{display:grid;grid-template-columns:290px 1fr;gap:18px;margin-top:18px}
.lesson-side{padding:16px;max-height:76vh;overflow:auto}
.lesson-side h4{font-size:.8rem;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);margin:14px 8px 6px}
.lesson-side button{display:flex;justify-content:space-between;width:100%;text-align:left;background:none;border:none;color:var(--text);padding:9px 12px;border-radius:10px;cursor:pointer;font-size:.9rem}
.lesson-side button:hover{background:var(--card)}
.lesson-side button.active{background:linear-gradient(135deg,rgba(124,108,255,.25),rgba(45,212,191,.12));color:#fff}
.lesson-side .tick{color:var(--acc2)}
.lesson-body{padding:30px;min-height:60vh}
.lesson-body h3{font-size:1.5rem;margin-bottom:4px}
.lesson-body .lvl-tag{color:var(--muted);font-size:.85rem;margin-bottom:18px;display:block}
.lesson-body p{line-height:1.75;color:var(--text);margin:12px 0}
.lesson-body .codeblock{background:#0b0e1a;border:1px solid var(--border);border-radius:12px;padding:16px;margin:16px 0;font-family:monospace;font-size:.88rem;color:#9be9d8;white-space:pre-wrap;line-height:1.7}
body.light .lesson-body .codeblock{background:#101626;color:#9be9d8}
.lesson-actions{display:flex;gap:12px;margin-top:26px;flex-wrap:wrap}
.tip{border-left:3px solid var(--acc2);padding:10px 14px;background:rgba(45,212,191,.07);border-radius:0 10px 10px 0;color:var(--muted);font-size:.9rem;margin:14px 0}

/* PLAYGROUND */
.split{display:grid;grid-template-columns:1fr 1fr;gap:18px;margin-top:10px}
.term{padding:14px;height:480px;display:flex;flex-direction:column;font-family:'JetBrains Mono',Consolas,monospace;font-size:.86rem}
.term-out{flex:1;overflow:auto;white-space:pre-wrap;line-height:1.6}
.term-out .cmdline{color:var(--acc2)}
.term-out .err{color:#f87171}
.term-out .ok{color:#9be9d8}
.term-out .dim{color:var(--muted)}
.term-in{display:flex;gap:8px;align-items:center;border-top:1px solid var(--border);padding-top:10px;margin-top:8px}
.term-in .ps1{color:var(--pink);white-space:nowrap}
.term-in input{flex:1;background:none;border:none;outline:none;color:var(--text);font:inherit}
.term-hint{font-size:.75rem;color:var(--muted);margin-top:6px;min-height:16px}
.graph{padding:14px;height:480px;display:flex;flex-direction:column;position:relative}
.graph-head{display:flex;justify-content:space-between;align-items:center;margin-bottom:8px}
#graphSvg{flex:1;width:100%}
.graph-empty{position:absolute;inset:50px 20px 20px;display:grid;place-items:center;color:var(--muted);text-align:center}
.edge{fill:none;stroke:rgba(150,160,200,.45);stroke-width:2.5}
.node circle{filter:drop-shadow(0 0 10px rgba(124,108,255,.55));stroke:rgba(255,255,255,.6);stroke-width:1.5}
.node.pop circle{animation:pop .5s cubic-bezier(.2,1.6,.4,1)}
@keyframes pop{from{transform:scale(0)}to{transform:scale(1)}}
.cid{fill:#fff;font-size:9px;text-anchor:middle;font-family:monospace}
.cmsg{fill:var(--muted);font-size:10px;text-anchor:middle}
.blabel{fill:rgba(124,108,255,.25);stroke:var(--acc)}
.blabel.head{fill:rgba(45,212,191,.3);stroke:var(--acc2)}
.btext{fill:var(--text);font-size:11px;font-family:monospace}

/* EXPLORER */
.search{width:100%;max-width:520px;padding:14px 18px;color:var(--text);font-size:.95rem;outline:none;margin-bottom:20px}
.cmd-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:14px}
.cmd-card{padding:18px;border-radius:14px;background:var(--card);border:1px solid var(--border);cursor:pointer;transition:.22s}
.cmd-card:hover{transform:translateY(-3px);border-color:rgba(124,108,255,.5)}
.cmd-card .lvl{font-size:.7rem;padding:3px 9px;border-radius:99px;float:right}
.lvl.l1,.lvl.l2{background:rgba(45,212,191,.15);color:var(--acc2)}
.lvl.l3,.lvl.l4{background:rgba(124,108,255,.18);color:#b7adff}
.lvl.l5,.lvl.l6{background:rgba(244,114,182,.15);color:var(--pink)}
.cmd-card h3{font-family:monospace;font-size:1.02rem;color:var(--acc2)}
.cmd-card p{color:var(--muted);font-size:.86rem;margin-top:8px;line-height:1.55}
.cmd-detail{grid-column:1/-1;padding:24px;border-radius:14px;background:var(--glass);border:1px solid rgba(124,108,255,.4);animation:fadeUp .3s ease}
.cmd-detail h3{font-family:monospace;color:var(--acc2);font-size:1.3rem}
.cmd-detail .row{margin:14px 0}
.cmd-detail .row b{color:var(--text);display:block;margin-bottom:5px;font-size:.85rem;text-transform:uppercase;letter-spacing:.06em}
.cmd-detail .row div{color:var(--muted);line-height:1.65;font-size:.92rem}
.cmd-detail .codeblock{background:#0b0e1a;border-radius:10px;padding:12px 16px;font-family:monospace;font-size:.85rem;color:#9be9d8;white-space:pre-wrap;line-height:1.7}

/* QUIZ */
.quiz-card{max-width:680px;margin:20px auto;padding:30px}
.quiz-card .qnum{color:var(--muted);font-size:.85rem;margin-bottom:10px}
.quiz-card h3{font-size:1.2rem;line-height:1.5;margin-bottom:20px}
.opts{display:flex;flex-direction:column;gap:10px}
.opt{padding:14px 18px;border-radius:12px;border:1px solid var(--border);background:var(--card);color:var(--text);text-align:left;cursor:pointer;font-size:.95rem;transition:.18s}
.opt:hover{border-color:var(--acc)}
.opt.right{border-color:var(--acc2);background:rgba(45,212,191,.12)}
.opt.wrong{border-color:#f87171;background:rgba(248,113,113,.1)}
.fill-in{width:100%;padding:14px 18px;border-radius:12px;border:1px solid var(--border);background:var(--card);color:var(--text);font-family:monospace;font-size:.95rem;outline:none}
.quiz-pick{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:14px;margin-top:20px}
.score-big{font-size:3rem;font-weight:800}
.celebrate{animation:celebrate .8s ease}
@keyframes celebrate{0%{transform:scale(.6);opacity:0}60%{transform:scale(1.12)}100%{transform:scale(1);opacity:1}}

/* DASHBOARD */
.dash-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:16px;margin-top:18px}
.dash-card{padding:22px;text-align:center}
.dash-card h4{color:var(--muted);font-size:.82rem;text-transform:uppercase;letter-spacing:.07em;margin-bottom:14px}
.ring{transform:rotate(-90deg)}
.ring .track{stroke:var(--card);fill:none;stroke-width:9}
.ring .bar{stroke:#2dd4bf;fill:none;stroke-width:9;stroke-linecap:round;transition:stroke-dashoffset 1s cubic-bezier(.2,.8,.2,1)}
.ring-wrap{position:relative;display:inline-block}
.ring-num{position:absolute;inset:0;display:grid;place-items:center;font-weight:800;font-size:1.25rem}
.heatmap{display:grid;grid-template-rows:repeat(7,12px);grid-auto-flow:column;gap:3px;justify-content:center;margin-top:14px}
.heatmap i{width:12px;height:12px;border-radius:3px;background:var(--card)}
.heatmap i.h1{background:rgba(45,212,191,.35)}.heatmap i.h2{background:rgba(45,212,191,.6)}.heatmap i.h3{background:var(--acc2)}
.badges{display:grid;grid-template-columns:repeat(auto-fill,minmax(170px,1fr));gap:12px;margin-top:14px}
.badge{padding:16px;text-align:center;border-radius:14px;background:var(--card);border:1px solid var(--border)}
.badge .bi{font-size:1.9rem;filter:grayscale(1);opacity:.4}
.badge.won .bi{filter:none;opacity:1;animation:pop .5s cubic-bezier(.2,1.6,.4,1)}
.badge h5{margin:8px 0 3px;font-size:.88rem}
.badge p{font-size:.74rem;color:var(--muted)}

/* TOASTS */
#toasts{position:fixed;bottom:22px;right:22px;display:flex;flex-direction:column;gap:10px;z-index:99}
.toast{padding:14px 20px;border-radius:13px;background:var(--glass);backdrop-filter:blur(12px);border:1px solid rgba(124,108,255,.5);box-shadow:var(--shadow);animation:toastIn .4s cubic-bezier(.2,1.4,.4,1);font-size:.9rem;max-width:320px}
@keyframes toastIn{from{transform:translateX(120%)}to{transform:none}}

.footer{text-align:center;color:var(--muted);font-size:.85rem;padding:30px 0 40px}

@media(max-width:920px){
  .hero{grid-template-columns:1fr}.hero-visual{height:300px}
  .split{grid-template-columns:1fr}
  .lessons-layout{grid-template-columns:1fr}.lesson-side{max-height:240px}
  .menu{order:3;width:100%;justify-content:flex-start;overflow-x:auto}
  .nav{flex-wrap:wrap;border-radius:20px;top:6px}
}