:root{
    --bg:#070a10; --bg-grad:#0a0f18;
    --panel:#0c1220; --panel-2:#0f1725; --panel-3:#131d2e;
    --line:#1b2536; --line-2:#26344a;
    --text:#cbd5e6; --muted:#7486a0; --dim:#465468;
    --signal:#4ff0a5; --signal-soft:rgba(79,240,165,.12); --signal-line:rgba(79,240,165,.35);
    --cyan:#46cbe8; --cyan-soft:rgba(70,203,232,.12);
    --amber:#f5b13d; --amber-soft:rgba(245,177,61,.12);
    --danger:#ff5a48; --danger-soft:rgba(255,90,72,.13);
    --violet:#9d7bff;
    --mono:ui-monospace,"Cascadia Code","JetBrains Mono","SF Mono",Menlo,Consolas,monospace;
    --sans:"Segoe UI",system-ui,-apple-system,Roboto,"Helvetica Neue",sans-serif;
    --r:10px;
  }
  *{box-sizing:border-box}
  html,body{height:100%}
  body{
    margin:0; background:
      radial-gradient(1100px 700px at 78% -8%, #0e1a2b 0%, transparent 60%),
      radial-gradient(900px 600px at 0% 110%, #0c1622 0%, transparent 55%),
      var(--bg);
    color:var(--text); font-family:var(--sans);
    -webkit-font-smoothing:antialiased; text-rendering:optimizeLegibility;
    overflow:hidden;
  }
  .app{display:flex; flex-direction:column; height:100dvh; min-height:0}

  /* ---------- Top bar ---------- */
  .topbar{
    display:flex; align-items:center; gap:18px; flex-wrap:wrap;
    padding:11px 18px; border-bottom:1px solid var(--line);
    background:linear-gradient(180deg, rgba(255,255,255,.02), transparent);
  }
  .brand{display:flex; align-items:center; gap:11px; flex:0 0 auto}
  .brand .dot{width:9px;height:9px;border-radius:50%;background:var(--signal);
    box-shadow:0 0 10px 1px var(--signal); animation:beat 2.4s ease-in-out infinite}
  @keyframes beat{0%,100%{opacity:1}50%{opacity:.35}}
  .brand b{font-family:var(--mono); font-weight:700; letter-spacing:.14em; font-size:14px}
  .brand span{color:var(--muted); font-family:var(--mono); font-size:12px; letter-spacing:.14em}

  .steps{display:flex; align-items:center; gap:2px; margin:0 auto; overflow-x:auto; max-width:100%;
    scrollbar-width:none; -ms-overflow-style:none}
  .steps::-webkit-scrollbar{display:none}
  .step{display:flex; align-items:center; gap:8px; padding:5px 11px; border-radius:20px;
    white-space:nowrap; color:var(--dim); font-family:var(--mono); font-size:11.5px; letter-spacing:.06em;
    transition:.35s}
  .step .n{display:grid;place-items:center; width:19px;height:19px;border-radius:50%;
    border:1.5px solid currentColor; font-size:10.5px; font-weight:700}
  .step.active{color:var(--signal); background:var(--signal-soft)}
  .step.done{color:var(--muted)}
  .step.done .n{background:var(--signal-soft); border-color:var(--signal-line); color:var(--signal)}
  .step .arrow{color:var(--line-2)}

  .safebadge{flex:0 0 auto; display:flex;align-items:center;gap:7px; font-family:var(--mono);
    font-size:11px; letter-spacing:.1em; color:var(--signal); border:1px solid var(--signal-line);
    padding:5px 10px; border-radius:20px; background:var(--signal-soft)}
  .safebadge .ico{width:7px;height:7px;border-radius:2px;background:var(--signal)}

  /* ---------- Main grid ---------- */
  .main{flex:1; min-height:0; display:grid; grid-template-columns:minmax(0,1.05fr) minmax(0,1fr);
    gap:14px; padding:14px 18px 0}
  .col{min-height:0; min-width:0; display:flex; flex-direction:column; gap:14px}

  .card{background:linear-gradient(180deg,var(--panel-2),var(--panel));
    border:1px solid var(--line); border-radius:var(--r); min-height:0; min-width:0; display:flex; flex-direction:column}
  .card-h{display:flex; align-items:center; gap:10px; padding:9px 13px; border-bottom:1px solid var(--line);
    font-family:var(--mono); font-size:12px; letter-spacing:.08em; color:var(--muted)}
  .card-h .tt{color:var(--text)}
  .card-h .rt{margin-left:auto; display:flex; gap:6px; align-items:center}
  .lamp{width:9px;height:9px;border-radius:50%;background:var(--line-2)}
  .lamp.r{background:#ff5f56}.lamp.y{background:#ffbd2e}.lamp.g{background:#27c93f}

  /* ---------- Terminal ---------- */
  .term-card{flex:1}
  .term{flex:1; overflow-y:auto; padding:13px 15px; font-family:var(--mono);
    font-size:12.5px; line-height:1.62; white-space:pre-wrap; word-break:break-word}
  .term::-webkit-scrollbar{width:9px}.term::-webkit-scrollbar-thumb{background:var(--line-2);border-radius:9px}
  .term .l{margin:0}
  .p-user{color:var(--signal)} .p-host{color:var(--cyan)} .p-path{color:var(--amber)}
  .p-tree{color:var(--dim)}
  .cmd{color:#eaf1fb}
  .o{color:#9fb0c7}.o-dim{color:var(--dim)}.o-ok{color:var(--signal)}.o-warn{color:var(--amber)}
  .o-bad{color:var(--danger)}.o-key{color:var(--signal); font-weight:700}
  .o-head{color:var(--cyan)}
  .cur{display:inline-block;width:8px;height:15px;vertical-align:-2px;background:var(--signal);
    animation:blink 1s steps(1) infinite}
  @keyframes blink{50%{opacity:0}}
  .term .row{color:#a9b8cd}
  .term .hl{color:var(--amber)}

  /* ---------- Airspace canvas ---------- */
  .scene-card{flex:1}
  .scene-wrap{flex:1; position:relative; min-height:0; overflow:hidden; border-radius:0 0 var(--r) var(--r)}
  canvas{position:absolute; inset:0; width:100%; height:100%; display:block}
  .scene-tag{position:absolute; left:12px; bottom:11px; font-family:var(--mono); font-size:10.5px;
    letter-spacing:.1em; color:var(--dim)}
  .capchip{position:absolute; right:12px; top:12px; display:none; align-items:center; gap:8px;
    font-family:var(--mono); font-size:11px; letter-spacing:.05em; color:var(--signal);
    background:var(--signal-soft); border:1px solid var(--signal-line); padding:6px 10px; border-radius:8px}
  .capchip.show{display:flex; animation:pop .4s ease}
  @keyframes pop{from{transform:scale(.9);opacity:0}to{transform:scale(1);opacity:1}}

  /* ---------- Networks list ---------- */
  .nets{padding:8px; overflow-y:auto; display:flex; flex-direction:column; gap:7px; min-height:0}
  .nets::-webkit-scrollbar{width:9px}.nets::-webkit-scrollbar-thumb{background:var(--line-2);border-radius:9px}
  .net{display:grid; grid-template-columns:22px 1fr auto; align-items:center; gap:11px;
    padding:10px 12px; border:1px solid var(--line); border-radius:9px; background:var(--panel);
    font-family:var(--mono); opacity:0; transform:translateY(6px); transition:.18s}
  .net.in{opacity:1; transform:none}
  .net.sel-on{cursor:pointer}
  .net.sel-on:hover{border-color:var(--line-2); background:var(--panel-3)}
  .net.picked{border-color:var(--signal-line); background:var(--signal-soft); cursor:default}
  .net.target .badge{display:inline-block}
  .net .sig{display:flex; align-items:flex-end; gap:2px; height:18px}
  .net .sig i{width:3px; background:var(--dim); border-radius:1px}
  .net.picked .sig i, .net:hover .sig i{background:var(--signal)}
  .net .nm{display:flex; flex-direction:column; gap:3px; min-width:0}
  .net .nm b{font-size:12.5px; color:var(--text); font-family:var(--sans); font-weight:600}
  .net .nm small{color:var(--muted); font-size:11px; letter-spacing:.03em; overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
  .net .badge{display:none; font-size:9px; letter-spacing:.12em; color:var(--amber);
    border:1px solid var(--amber-soft); background:var(--amber-soft); padding:2px 6px; border-radius:5px; margin-left:8px}
  .net .enc{font-size:10.5px; color:var(--muted); text-align:right; letter-spacing:.04em}
  .net .enc.open{color:var(--danger)}
  .net.picked .enc{color:var(--signal)}

  /* ---------- Guide + action ---------- */
  .console{flex:0 0 auto; display:grid; grid-template-columns:1fr auto; gap:14px; align-items:stretch;
    padding:14px 18px 16px}
  .guide{background:linear-gradient(180deg,var(--panel-2),var(--panel)); border:1px solid var(--line);
    border-radius:var(--r); padding:13px 16px; display:flex; flex-direction:column; gap:6px; min-width:0}
  .guide .k{font-family:var(--mono); font-size:11px; letter-spacing:.14em; color:var(--signal);
    display:flex; align-items:center; gap:8px}
  .guide .k .idx{color:var(--dim)}
  .guide h3{margin:0; font-size:15.5px; font-weight:650; letter-spacing:.01em; text-wrap:balance}
  .guide p{margin:0; color:var(--muted); font-size:13px; line-height:1.5; max-width:60ch}
  .guide p b{color:var(--text); font-weight:600}
  .guide code{font-family:var(--mono); color:var(--amber); font-size:12px}

  .actions{display:flex; flex-direction:column; justify-content:center; gap:9px; min-width:212px}
  .btn{appearance:none; border:0; cursor:pointer; font-family:var(--mono); font-weight:600;
    letter-spacing:.04em; font-size:13px; padding:14px 18px; border-radius:10px; color:#04140c;
    background:linear-gradient(180deg,#6bffbb,var(--signal)); box-shadow:0 6px 22px -8px var(--signal);
    display:flex; align-items:center; justify-content:center; gap:9px; transition:.16s; text-align:center}
  .btn:hover:not(:disabled){transform:translateY(-1px); box-shadow:0 10px 26px -8px var(--signal)}
  .btn:active:not(:disabled){transform:translateY(0)}
  .btn:disabled{opacity:.4; cursor:not-allowed; filter:saturate(.4)}
  .btn.ghost{background:transparent; color:var(--muted); border:1px solid var(--line-2); box-shadow:none;
    padding:10px 14px; font-size:12px}
  .btn.ghost:hover:not(:disabled){color:var(--text); border-color:var(--muted); transform:none; box-shadow:none}
  .btn .spin{width:13px;height:13px;border-radius:50%;border:2px solid rgba(4,20,12,.35);
    border-top-color:#04140c; animation:sp .7s linear infinite}
  @keyframes sp{to{transform:rotate(360deg)}}
  .hint{font-family:var(--mono); font-size:10.5px; letter-spacing:.05em; color:var(--dim); text-align:center}

  /* ---------- Intro overlay ---------- */
  .overlay{position:fixed; inset:0; z-index:40; display:grid; place-items:center; padding:24px;
    background:radial-gradient(900px 600px at 50% 0%, #0d1626 0%, transparent 60%), rgba(5,8,13,.92);
    backdrop-filter:blur(3px)}
  .intro{width:min(880px,100%); border:1px solid var(--line-2); border-radius:16px; overflow:hidden;
    background:linear-gradient(180deg,var(--panel-2),var(--panel)); box-shadow:0 40px 120px -40px #000}
  .intro-grid{display:grid; grid-template-columns:1.25fr .9fr}
  .intro-l{padding:34px 34px 30px; display:flex; flex-direction:column; gap:16px; min-width:0}
  .kicker{font-family:var(--mono); font-size:11.5px; letter-spacing:.22em; color:var(--signal)}
  .intro h1{margin:0; font-size:33px; line-height:1.05; letter-spacing:-.01em; text-wrap:balance;
    font-weight:700}
  .intro h1 em{font-style:normal; color:var(--signal)}
  .intro .lede{margin:0; color:var(--muted); font-size:14px; line-height:1.6; max-width:46ch}
  .flow{display:flex; flex-wrap:wrap; gap:7px; margin-top:2px}
  .flow span{font-family:var(--mono); font-size:11px; letter-spacing:.04em; color:var(--muted);
    border:1px solid var(--line-2); border-radius:20px; padding:5px 11px}
  .flow span b{color:var(--signal); font-weight:700; margin-right:5px}
  .nickfield{display:flex; flex-direction:column; gap:7px; margin-top:2px}
  .nick-k{font-family:var(--mono); font-size:11px; letter-spacing:.16em; color:var(--signal)}
  .nickfield input{font-family:var(--sans); font-size:16px; color:var(--text);
    background:var(--panel); border:1px solid var(--line-2); border-radius:10px;
    padding:12px 14px; width:100%; max-width:340px; outline:none; transition:.16s}
  .nickfield input:focus{border-color:var(--signal-line); box-shadow:0 0 0 3px var(--signal-soft)}
  .nick-h{font-family:var(--mono); font-size:10.5px; color:var(--dim); letter-spacing:.02em}
  .intro-cta{display:flex; gap:12px; align-items:center; margin-top:6px; flex-wrap:wrap}
  .disc{font-family:var(--mono); font-size:10.5px; color:var(--dim); letter-spacing:.03em; line-height:1.5;
    border-top:1px solid var(--line); padding-top:13px; margin-top:2px}
  .disc b{color:var(--amber)}

  .intro-r{border-left:1px solid var(--line); padding:30px 26px; display:flex; flex-direction:column;
    align-items:center; justify-content:center; gap:14px; text-align:center;
    background:radial-gradient(400px 300px at 50% 20%, rgba(79,240,165,.05), transparent 70%)}
  .qr-label{font-family:var(--mono); font-size:11px; letter-spacing:.12em; color:var(--signal)}
  .qr-frame{background:#fff; padding:12px; border-radius:12px; line-height:0;
    box-shadow:0 0 0 1px var(--line-2), 0 20px 50px -20px #000}
  .qr-frame canvas{position:static; width:180px; height:180px; image-rendering:pixelated}
  .qr-sub{font-family:var(--mono); font-size:10.5px; color:var(--muted); letter-spacing:.02em; max-width:210px;
    line-height:1.5}
  .qr-url{font-family:var(--mono); font-size:10px; color:var(--dim); word-break:break-all; max-width:220px}

  /* ---------- Debrief ---------- */
  .debrief{position:fixed; inset:0; z-index:35; display:none; place-items:center; padding:24px; overflow:auto;
    background:radial-gradient(900px 600px at 50% 0%, #0d1626 0%, transparent 60%), rgba(5,8,13,.94)}
  .debrief.show{display:grid}
  .db{width:min(900px,100%); border:1px solid var(--line-2); border-radius:16px; overflow:hidden;
    background:linear-gradient(180deg,var(--panel-2),var(--panel))}
  .db-top{padding:28px 30px; border-bottom:1px solid var(--line); display:flex; align-items:center; gap:22px;
    flex-wrap:wrap}
  .db-top h2{margin:0 0 5px; font-size:22px; letter-spacing:-.01em}
  .db-top p{margin:0; color:var(--muted); font-size:13px}
  .keybox{margin-left:auto; text-align:right; font-family:var(--mono)}
  .keybox small{display:block; color:var(--muted); font-size:10.5px; letter-spacing:.14em}
  .keybox .val{font-size:24px; color:var(--signal); font-weight:700; letter-spacing:.02em}
  .db-body{display:grid; grid-template-columns:1fr 1fr; gap:0}
  .db-col{padding:22px 26px}
  .db-col+.db-col{border-left:1px solid var(--line)}
  .db-col h4{margin:0 0 14px; font-family:var(--mono); font-size:11px; letter-spacing:.14em}
  .db-col.recap h4{color:var(--cyan)} .db-col.defend h4{color:var(--signal)}
  .db-list{list-style:none; margin:0; padding:0; display:flex; flex-direction:column; gap:12px}
  .db-list li{display:grid; grid-template-columns:20px 1fr; gap:11px; font-size:12.5px; line-height:1.45; color:var(--muted)}
  .db-list li b{color:var(--text); font-weight:600}
  .db-list .m{font-family:var(--mono); font-size:11px; color:var(--dim)}
  .db-list .tick{position:relative; display:inline-block; width:13px; height:13px; margin-top:2px}
  .db-list .tick::after{content:""; position:absolute; left:4px; top:0; width:4px; height:8px;
    border:solid var(--signal); border-width:0 2px 2px 0; transform:rotate(45deg)}
  .db-foot{padding:18px 26px; border-top:1px solid var(--line); display:flex; gap:12px; align-items:center;
    flex-wrap:wrap}
  .db-foot .note{font-family:var(--mono); font-size:11px; color:var(--dim); flex:1; min-width:200px}

  /* ---------------- Tablet & phone ---------------- */
  @media (max-width:920px){
    body{overflow-y:auto; overflow-x:hidden; -webkit-text-size-adjust:100%}
    .app{height:auto; min-height:100dvh; width:100%; overflow-x:hidden}

    /* header sticks so the stage stepper stays visible while scrolling */
    .topbar{position:sticky; top:0; z-index:25; order:0; padding:10px 14px; gap:10px;
      background:linear-gradient(180deg, rgba(9,13,20,.94), rgba(9,13,20,.82)); backdrop-filter:blur(8px)}
    .steps{order:3; width:100%; justify-content:flex-start; padding-bottom:1px}

    /* stack + reorder: instruction first, visual next, terminal last */
    .console{order:1; grid-template-columns:1fr; padding:12px 12px 0; gap:0}
    .main{order:2; grid-template-columns:1fr; padding:12px; gap:12px;
      padding-bottom:calc(134px + env(safe-area-inset-bottom))}
    .main > .col:nth-child(1){order:2}   /* terminal */
    .main > .col:nth-child(2){order:1}   /* airspace + networks */

    .term{max-height:38vh}
    .scene-wrap{height:38vh; min-height:230px; flex:none}
    .nets{max-height:46vh}

    /* primary action pinned to the bottom, in thumb reach, always visible */
    .actions{position:fixed; left:0; right:0; bottom:0; z-index:30; min-width:0;
      flex-direction:column; gap:8px; align-items:stretch;
      padding:11px 14px calc(11px + env(safe-area-inset-bottom));
      background:linear-gradient(180deg, rgba(10,14,22,.55), var(--bg) 55%);
      border-top:1px solid var(--line); backdrop-filter:blur(12px)}
    .btn{width:100%; padding:15px 18px; font-size:14px; min-height:52px}
    .btn.ghost{width:100%; min-height:0; padding:11px}
    .hint{order:3}

    /* overlays: scroll from the top on short screens */
    .overlay{align-items:flex-start; overflow-y:auto; padding:14px}
    .intro-grid{grid-template-columns:1fr}
    .intro-l{padding:24px 20px 20px; gap:13px}
    .intro h1{font-size:25px}
    .intro-r{border-left:0; border-top:1px solid var(--line); padding:22px 20px}
    #startBtn{width:100%}
    .intro-cta{width:100%}

    .debrief{align-items:flex-start; overflow-y:auto}
    .db-top{padding:22px 20px}
    .db-body{grid-template-columns:1fr}
    .db-col{padding:20px}
    .db-col+.db-col{border-left:0; border-top:1px solid var(--line)}
    .keybox{margin-left:0; text-align:left}
    .db-foot{padding:16px 20px}
    .db-foot .btn, .db-foot #dbRestart{width:100%; min-width:0}
  }

  /* ---------------- Phones ---------------- */
  @media (max-width:600px){
    .brand span{display:none}                 /* hide "// WiFi Security Lab" subtitle */
    .safebadge{padding:5px 8px; font-size:10px}
    .step{padding:5px 9px; font-size:11px}
    .scene-wrap{height:34vh; min-height:210px}
    .term{max-height:34vh}
    .guide h3{font-size:15px}
    .guide p{font-size:12.5px}
    .intro-r{display:none}                     /* students already scanned — drop the QR panel */
    .intro h1{font-size:23px}
    .flow span{font-size:10.5px; padding:5px 9px}
    .db-top h2{font-size:19px}
    .keybox .val{font-size:21px}
  }
  @media (prefers-reduced-motion:reduce){
    *{animation-duration:.001s !important; transition-duration:.001s !important}
  }