:root{
  --bg:#f3f6fb; --surface:#ffffff; --surface-2:#e9eff8; --ink:#14213d; --muted:#5a6782; --line:#d3dceb;
  --outcome:#15803d; --outcome-bg:#e2f4e8;
  --opp:#2563eb; --opp-bg:#e3ecfd;
  --sol:#b45309; --sol-bg:#fdf0dc;
  --test:#be185d; --test-bg:#fce7f1;
  --good:#15803d; --good-bg:#e1f4e8; --warn:#b45309; --warn-bg:#fdf1dc; --bad:#b91c1c; --bad-bg:#fbe4e4;
  --accent:#1d4ed8; --accent-ink:#fff;
  --shadow:0 1px 2px rgba(20,33,61,.06),0 6px 20px rgba(20,33,61,.08);
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --bg:#0f1523; --surface:#161e30; --surface-2:#1e2840; --ink:#e6ecf7; --muted:#9aa8c2; --line:#2b3754;
    --outcome:#6fd39a; --outcome-bg:#12301f; --opp:#7aa8ff; --opp-bg:#172a4f; --sol:#f0b45e; --sol-bg:#3a2a14; --test:#f49ac1; --test-bg:#3d1a2c;
    --good:#6fd39a; --good-bg:#12301f; --warn:#f0c060; --warn-bg:#3a2f14; --bad:#f08a80; --bad-bg:#3d1f1b;
    --accent:#7aa8ff; --accent-ink:#0b1220; --shadow:0 1px 2px rgba(0,0,0,.35),0 6px 20px rgba(0,0,0,.3);
  }
}
:root[data-theme="dark"]{
  --bg:#0f1523; --surface:#161e30; --surface-2:#1e2840; --ink:#e6ecf7; --muted:#9aa8c2; --line:#2b3754;
    --outcome:#6fd39a; --outcome-bg:#12301f; --opp:#7aa8ff; --opp-bg:#172a4f; --sol:#f0b45e; --sol-bg:#3a2a14; --test:#f49ac1; --test-bg:#3d1a2c;
    --good:#6fd39a; --good-bg:#12301f; --warn:#f0c060; --warn-bg:#3a2f14; --bad:#f08a80; --bad-bg:#3d1f1b;
    --accent:#7aa8ff; --accent-ink:#0b1220; --shadow:0 1px 2px rgba(0,0,0,.35),0 6px 20px rgba(0,0,0,.3);
}
*{box-sizing:border-box}
html,body{margin:0}
body{background:var(--bg);color:var(--ink);font:16px/1.55 Inter,system-ui,sans-serif;min-height:100vh}
h1,h2,h3,h4{font-family:Fraunces,Georgia,serif;font-weight:700;line-height:1.2;margin:0}
button{font:inherit;color:inherit;cursor:pointer}
a{color:var(--accent)}
.wrap{max-width:1180px;margin:0 auto;padding:20px 16px 48px}
header.top{display:flex;align-items:center;gap:16px;flex-wrap:wrap;margin-bottom:18px}
.brand{display:flex;align-items:center;gap:10px;margin-right:auto;background:none;border:0;padding:0;text-align:left}
.brand svg{flex:none}
.brand h1{font-size:1.35rem}
.brand small{display:block;color:var(--muted);font-size:.8rem;font-family:Inter,sans-serif;font-weight:500}
.hud{display:flex;gap:10px;align-items:center;flex-wrap:wrap}
.pill{background:var(--surface);border:1px solid var(--line);border-radius:999px;padding:6px 12px;font-size:.85rem;font-weight:600;white-space:nowrap}
.pill:empty{display:none}
.icon-btn{background:var(--surface);border:1px solid var(--line);border-radius:999px;width:36px;height:36px;display:grid;place-items:center}
.progress{display:flex;gap:4px;margin:0 0 18px}
.progress span{flex:1;height:6px;border-radius:3px;background:var(--line)}
.progress span.done{background:var(--accent)}
.progress span.now{background:var(--opp)}
.grid{display:grid;grid-template-columns:minmax(0,1.1fr) minmax(0,1fr);gap:20px;align-items:start}
.grid>*{min-width:0}
@media (max-width:900px){.grid{grid-template-columns:minmax(0,1fr)}}
.card{background:var(--surface);border:1px solid var(--line);border-radius:16px;box-shadow:var(--shadow);padding:22px}
.eyebrow{font-size:.75rem;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);font-weight:600;margin-bottom:6px}
.card h2{font-size:1.5rem;margin-bottom:10px}
.lead{color:var(--muted);margin:0 0 16px}
.scenario{background:var(--surface-2);border-radius:12px;padding:12px 14px;margin:0 0 16px;font-size:.95rem}
.q{font-weight:600;margin:6px 0 12px}
.opts{display:grid;gap:10px}
.opt{text-align:left;background:var(--surface);border:1.5px solid var(--line);border-radius:12px;padding:12px 14px;transition:border-color .15s,background .15s,transform .05s}
.opt:hover:not([disabled]){border-color:var(--accent)}
.opt:active:not([disabled]){transform:translateY(1px)}
.opt[disabled]{cursor:default}
.opt.sel{border-color:var(--sol);background:var(--sol-bg)}
.opt.correct{border-color:var(--good);background:var(--good-bg)}
.opt.partial{border-color:var(--warn);background:var(--warn-bg)}
.opt.wrong{border-color:var(--bad);background:var(--bad-bg)}
.opt .meta{display:block;font-size:.82rem;color:var(--muted);margin-top:6px}
.bars{display:grid;grid-template-columns:auto 1fr;gap:4px 10px;align-items:center;margin-top:8px;font-size:.78rem;color:var(--muted)}
.bar{height:6px;background:var(--line);border-radius:3px;overflow:hidden}
.bar i{display:block;height:100%;background:var(--opp)}
.feedback{margin-top:14px;border-radius:12px;padding:12px 14px;font-size:.95rem;display:none}
.feedback.show{display:block;animation:pop .2s ease}
.feedback.good{background:var(--good-bg);border-left:4px solid var(--good)}
.feedback.partial{background:var(--warn-bg);border-left:4px solid var(--warn)}
.feedback.bad{background:var(--bad-bg);border-left:4px solid var(--bad)}
.feedback b{display:block;margin-bottom:2px}
@keyframes pop{from{opacity:0;transform:translateY(4px)}to{opacity:1;transform:none}}
.actions{display:flex;gap:10px;justify-content:flex-end;margin-top:16px;flex-wrap:wrap}
.btn{background:var(--accent);color:var(--accent-ink);border:0;border-radius:999px;padding:10px 18px;font-weight:600;text-decoration:none;display:inline-block}
.btn.ghost{background:transparent;color:var(--ink);border:1.5px solid var(--line)}
.btn.small{padding:6px 12px;font-size:.85rem}
.btn[disabled]{opacity:.45;cursor:not-allowed}
.linkbtn{background:none;border:0;color:var(--muted);text-decoration:underline;padding:0;font-size:.85rem}
.sortcard{border:1.5px dashed var(--line);border-radius:14px;padding:18px;text-align:center;font-family:Fraunces,Georgia,serif;font-size:1.15rem;margin-bottom:14px;background:var(--surface-2);min-height:84px;display:grid;place-items:center}
.counter{font-size:.82rem;color:var(--muted);text-align:center;margin-bottom:8px}
.buckets{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:8px}
.bucket{border:1.5px solid var(--line);background:var(--surface);border-radius:12px;padding:10px;font-weight:600;font-size:.92rem}
.bucket small{display:block;font-weight:400;color:var(--muted);font-size:.78rem;margin-top:2px}
.bucket:hover:not([disabled]){border-color:var(--accent)}
.bucket.correct{border-color:var(--good);background:var(--good-bg)}
.bucket.wrong{border-color:var(--bad);background:var(--bad-bg)}
.habit{margin-top:18px;border-top:1px solid var(--line);padding-top:14px;font-size:.88rem;color:var(--muted)}
.habit strong{color:var(--ink)}

/* tree panel */
.treepanel{position:sticky;top:16px}
@media (max-width:900px){.treepanel{position:static}}
.treepanel h3{font-size:1.1rem;margin-bottom:4px}
.legend{display:flex;gap:10px;flex-wrap:wrap;font-size:.75rem;color:var(--muted);margin:6px 0 12px}
.legend span::before{content:"";display:inline-block;width:10px;height:10px;border-radius:3px;margin-right:5px;vertical-align:-1px;background:var(--c)}
.treescroll{overflow-x:auto;padding:4px 0 8px}
.treefit{transform-origin:top left}
.tree{display:flex;flex-direction:column;align-items:center;width:max-content;margin:0 auto}
.tree ul{display:flex;justify-content:center;padding:16px 0 0;margin:0;position:relative;list-style:none}
.tree li{display:flex;flex-direction:column;align-items:center;position:relative;padding:16px 3px 0}
.tree li::before,.tree li::after{content:"";position:absolute;top:0;width:50%;height:16px;border-top:1.5px solid var(--line)}
.tree li::before{right:50%}
.tree li::after{left:50%;border-left:1.5px solid var(--line)}
.tree li:only-child::before,.tree li:only-child::after{border-top:0}
.tree li:first-child::before,.tree li:last-child::after{border-top:0}
.tree li:last-child::before{border-right:1.5px solid var(--line);border-radius:0 6px 0 0}
.tree li:first-child::after{border-radius:6px 0 0 0}
.tree li:only-child::after{border-radius:0}
.tree ul::before{content:"";position:absolute;top:0;left:50%;height:16px;border-left:1.5px solid var(--line)}
.node{border-radius:10px;padding:6px 7px;font-size:.72rem;line-height:1.3;width:max-content;max-width:100px;text-align:center;border:1.5px solid;animation:grow .35s ease;overflow-wrap:anywhere}
.node.outcome{max-width:220px;font-size:.8rem;font-weight:600;background:var(--outcome-bg);border-color:var(--outcome);color:var(--ink)}
.node.opp{background:var(--opp-bg);border-color:var(--opp)}
.node.parent{font-weight:600}
.node.target{box-shadow:0 0 0 3px var(--opp);font-weight:600}
.node.target::before{content:"🎯 "}
.node.sol{background:var(--sol-bg);border-color:var(--sol)}
.node.test{background:var(--test-bg);border-color:var(--test)}
.node.empty{border-style:dashed;border-color:var(--line);color:var(--muted);background:transparent}
.noanim .node{animation:none}
.stepnav button.on.done::before{color:inherit}
@keyframes grow{from{opacity:0;transform:scale(.85)}to{opacity:1;transform:none}}
.parking{display:flex;flex-wrap:wrap;gap:6px;justify-content:center;margin-top:12px}
.parking .label{width:100%;text-align:center;font-size:.75rem;color:var(--muted)}
.treeempty{color:var(--muted);font-size:.9rem;text-align:center;padding:30px 10px}

/* home */
.hero{text-align:center;padding:34px 22px}
.hero h2{font-size:clamp(1.8rem,4vw,2.6rem);margin-bottom:12px}
.hero p{max-width:640px;margin:0 auto 14px;color:var(--muted)}
.steps{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:10px;margin:22px 0 8px;text-align:left}
.step{border-radius:12px;padding:12px;border:1.5px solid var(--c);background:var(--cb)}
.step b{display:block;font-family:Fraunces,Georgia,serif;font-size:1.02rem}
.step span{font-size:.82rem;color:var(--muted)}
.section-title{font-size:1.3rem;margin:28px 0 12px}
.scen-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:14px}
.scen{display:flex;flex-direction:column;gap:8px}
.scen .emoji{font-size:1.8rem;line-height:1}
.scen h3{font-size:1.15rem}
.scen p{margin:0;color:var(--muted);font-size:.92rem;flex:1}
.scen .tag{font-size:.75rem;font-weight:600;color:var(--muted);text-transform:uppercase;letter-spacing:.06em}
.scen .best{font-size:.8rem;color:var(--good);font-weight:600}
.builder-cta{display:grid;grid-template-columns:1fr auto;gap:16px;align-items:center;margin-top:14px;border-color:var(--opp);background:linear-gradient(135deg,var(--opp-bg),var(--surface) 70%)}
@media (max-width:640px){.builder-cta{grid-template-columns:1fr}}
.builder-cta h3{font-size:1.3rem;margin-bottom:4px}
.builder-cta p{margin:0;color:var(--muted)}
.score-big{font-family:Fraunces,Georgia,serif;font-size:3.2rem;font-weight:700;color:var(--accent);line-height:1}
.rank{font-weight:600;margin:6px 0 16px}
.recap{display:grid;gap:6px;text-align:left;max-width:560px;margin:16px auto}
.recap div{display:flex;justify-content:space-between;gap:10px;border-bottom:1px solid var(--line);padding:6px 0;font-size:.92rem}

/* workshop */
.stepnav{display:flex;gap:6px;overflow-x:auto;padding-bottom:6px;margin:-4px 0 16px}
.stepnav button{flex:none;border:1px solid var(--line);background:var(--surface);border-radius:999px;padding:4px 10px;font-size:.78rem;font-weight:600;color:var(--muted)}
.stepnav button.on{background:var(--accent);color:var(--accent-ink);border-color:var(--accent)}
.stepnav button.done{color:var(--ink)}
.stepnav button.done::before{content:"✓ ";color:var(--good)}
.field{display:block;margin:0 0 16px}
.field>span{display:block;font-weight:600;font-size:.95rem;margin-bottom:2px}
.field>small{display:block;color:var(--muted);font-size:.83rem;margin-bottom:6px}
input[type=text],input[type=time],textarea,select{width:100%;font:inherit;color:var(--ink);background:var(--surface);border:1.5px solid var(--line);border-radius:10px;padding:9px 11px}
textarea{min-height:64px;resize:vertical}
input:focus,textarea:focus,select:focus{outline:none;border-color:var(--accent);box-shadow:0 0 0 3px color-mix(in srgb,var(--accent) 20%,transparent)}
.row{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:10px}
.lint{font-size:.83rem;margin-top:6px;border-radius:8px;padding:6px 10px;display:none}
.lint.show{display:block}
.lint.warn{background:var(--warn-bg);color:var(--ink);border-left:3px solid var(--warn)}
.lint.ok{background:var(--good-bg);border-left:3px solid var(--good)}
.callout{border-radius:12px;padding:12px 14px;margin:0 0 16px;font-size:.92rem;border-left:4px solid var(--c,var(--accent));background:var(--cb,var(--surface-2))}
.callout b{display:block;margin-bottom:2px}
.callout.stop{--c:var(--bad);--cb:var(--bad-bg)}
.callout.remind{--c:var(--opp);--cb:var(--opp-bg)}
.callout.risk{--c:var(--test);--cb:var(--test-bg)}
.checklist{display:grid;gap:6px;margin:0 0 16px}
.checklist label{display:flex;gap:8px;align-items:flex-start;font-size:.92rem}
.checklist input{margin-top:4px;accent-color:var(--accent)}
.items{display:grid;gap:10px;margin:0 0 16px}
.item{border:1.5px solid var(--line);border-radius:12px;padding:10px 12px;background:var(--surface)}
.item.opp{border-left:4px solid var(--opp)}
.item.sol{border-left:4px solid var(--sol)}
.item.asm{border-left:4px solid var(--test)}
.item-head{display:flex;gap:8px;align-items:flex-start}
.item-head textarea,.item-head input{flex:1}
.x{border:0;background:transparent;color:var(--muted);font-size:1.1rem;line-height:1;padding:6px}
.x:hover{color:var(--bad)}
.addbox{border:1.5px dashed var(--line);border-radius:12px;padding:12px;margin:0 0 16px;background:var(--surface-2)}
.addbox .row{margin-top:8px}
.score-row{display:grid;grid-template-columns:150px 1fr 24px;gap:8px;align-items:center;font-size:.85rem;margin-top:6px}
.score-row input{width:100%;accent-color:var(--opp)}
.score-row output{font-weight:700;text-align:right}
@media (max-width:520px){.score-row{grid-template-columns:110px 1fr 20px}}
.total{display:flex;justify-content:space-between;align-items:center;margin-top:8px;gap:10px;flex-wrap:wrap}
.total b{font-family:Fraunces,Georgia,serif;font-size:1.1rem}
.radio{display:flex;gap:6px;align-items:center;font-weight:600;font-size:.9rem}
.radio input{accent-color:var(--opp)}
.chips{display:flex;gap:6px;flex-wrap:wrap;margin-top:6px}
.chip{font-size:.75rem;font-weight:600;border-radius:999px;padding:2px 9px;border:1px solid var(--line);color:var(--muted)}
.chip.on{background:var(--test-bg);border-color:var(--test);color:var(--ink)}
.chip.missing{border-style:dashed}
.riskgrid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:8px;margin:0 0 16px}
.riskcard{border-radius:12px;padding:10px 12px;background:var(--test-bg);border:1px solid var(--test);font-size:.85rem}
.riskcard b{display:block;font-size:.95rem;font-family:Fraunces,Georgia,serif}
.rank-badge{display:inline-block;min-width:24px;text-align:center;border-radius:999px;background:var(--test);color:var(--surface);font-weight:700;font-size:.78rem;padding:1px 7px;margin-right:6px}
.opener{font-family:Fraunces,Georgia,serif;font-size:1.05rem;background:var(--surface-2);border-radius:12px;padding:12px 14px;margin:0 0 12px}
.qnum{display:inline-grid;place-items:center;width:22px;height:22px;border-radius:50%;background:var(--opp-bg);color:var(--opp);font-size:.75rem;font-weight:700;margin-right:6px;border:1px solid var(--opp)}
ul.tips{margin:0 0 16px;padding-left:20px;font-size:.92rem}
ul.tips li{margin-bottom:4px}
.muted{color:var(--muted)}
footer{color:var(--muted);font-size:.8rem;text-align:center;margin-top:28px}
@media print{
  header.top,.progress,.stepnav,.actions,footer,#play{display:none!important}
  .grid{grid-template-columns:1fr}
  .card{box-shadow:none;border:0}
}

/* ---- workshop: saving, versions, failure loop ---- */
.wsbar{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin:-6px 0 14px;padding-bottom:12px;border-bottom:1px solid var(--line)}
.wsbar .saved{font-size:.8rem;color:var(--muted);margin-right:auto}
.versions{border:1px solid var(--line);border-radius:12px;padding:12px 14px;margin:0 0 14px;background:var(--surface-2)}
.ver{display:flex;flex-wrap:wrap;gap:6px;align-items:center;padding:8px 0;border-top:1px solid var(--line)}
.ver .vmeta{flex:1 1 220px;min-width:0}
.ver .vmeta input{padding:5px 8px;font-weight:600}
.ver .vmeta small{display:block;color:var(--muted);font-size:.76rem;margin-top:3px}
.toast{position:fixed;left:50%;bottom:24px;transform:translateX(-50%);background:var(--ink);color:var(--bg);padding:10px 18px;border-radius:999px;font-weight:600;font-size:.9rem;box-shadow:var(--shadow);z-index:50;animation:pop .2s ease;max-width:calc(100vw - 32px);text-align:center}
.callout{position:relative}
.callout.flash{padding-right:40px}
.callout>.x{position:absolute;top:6px;right:6px}
.callout.okc{--c:var(--good);--cb:var(--good-bg)}
.node.failed{opacity:.6;text-decoration:line-through;border-style:dashed;background:transparent}
.node.passed{box-shadow:0 0 0 2px var(--good)}
.legend .lg-failed::before{background:transparent;border:1.5px dashed var(--muted);box-sizing:border-box}
.item.failed{border-style:dashed;background:var(--surface-2)}
.item.failed>.item-head input[disabled]{text-decoration:line-through;color:var(--muted);background:transparent}
.chip.fail{background:var(--bad-bg);border-color:var(--bad);color:var(--ink)}
.chip.pass{background:var(--good-bg);border-color:var(--good);color:var(--ink)}
.chips .btn.small{padding:3px 10px;font-size:.78rem}
.seg{display:flex;gap:6px;flex-wrap:wrap;margin-bottom:10px}
.seg label{border:1.5px solid var(--line);border-radius:999px;padding:4px 11px;font-size:.85rem;font-weight:600;cursor:pointer;display:flex;gap:6px;align-items:center;background:var(--surface)}
.seg input{accent-color:var(--accent);margin:0}
.seg label:has(input:checked){border-color:var(--accent);background:var(--opp-bg)}
.loop{display:flex;flex-wrap:wrap;gap:6px;align-items:center;margin:8px 0 12px}
.loop .arrow{color:var(--muted)}
.log{display:grid;gap:8px;font-size:.88rem;margin:0 0 16px}
.log>div{border-left:3px solid var(--line);padding:2px 10px}
.log .fail{border-color:var(--bad)} .log .pass{border-color:var(--good)} .log .info{border-color:var(--opp)}

/* ---- resume / backup ---- */
.lastsession{margin-top:10px;font-size:.88rem;background:var(--surface);border:1px solid var(--line);border-radius:10px;padding:8px 10px}
.resume{display:grid;grid-template-columns:1fr 240px;gap:16px;align-items:center;margin-top:14px}
@media (max-width:640px){.resume{grid-template-columns:1fr}}
.resume h3{font-size:1.2rem;margin-bottom:4px}
.resume p{margin:0;color:var(--muted)}
.resume code{font-size:.85em;background:var(--surface-2);padding:1px 5px;border-radius:5px}
.dropzone{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:2px;border:2px dashed var(--opp);border-radius:14px;padding:18px 12px;background:var(--opp-bg);cursor:pointer;text-align:center;transition:background .15s,transform .1s}
.dropzone:hover,.dropzone.over{background:var(--surface);transform:translateY(-1px)}
.dropzone .dz-icon{font-size:1.4rem;color:var(--opp);line-height:1}
.dropzone small{color:var(--muted)}
.backup-nudge{margin:-4px 0 14px}

/* ---- open source card ---- */
.oss{display:grid;grid-template-columns:1fr auto;gap:16px;align-items:center;margin-top:14px}
@media (max-width:640px){.oss{grid-template-columns:1fr}}
.oss h3{font-size:1.2rem;margin-bottom:4px}
.oss p{margin:0;color:var(--muted)}
.oss code{font-size:.85em;background:var(--surface-2);padding:1px 5px;border-radius:5px}