/* Visual Labs: interactive, animated explainers injected into episodes by labs/*.js */
:root{
  --lab-bad:#ff6b6b;
  --lab-purple:#b794ff;
  --lab-glow:rgba(118,185,0,.18);
}
@media (prefers-color-scheme: light){
  :root:not([data-theme="dark"]){ --lab-bad:#c62828; --lab-purple:#6b3fd1; --lab-glow:rgba(78,140,0,.14); }
}
:root[data-theme="light"]{ --lab-bad:#c62828; --lab-purple:#6b3fd1; --lab-glow:rgba(78,140,0,.14); }

.lab{
  position:relative;margin:22px 0 26px;border-radius:16px;padding:1.5px;
  background:linear-gradient(135deg,var(--accent),var(--accent-2) 55%,var(--lab-purple));
  box-shadow:0 10px 40px -18px var(--lab-glow);
}
.lab-inner{background:var(--surface);border-radius:14.5px;padding:18px 20px 20px}
@media (max-width:600px){.lab-inner{padding:14px 12px 16px}}
.lab-head{display:flex;flex-direction:column;gap:6px;margin-bottom:14px}
.lab-badge{
  align-self:flex-start;display:inline-flex;align-items:center;gap:6px;font-family:var(--font-mono);
  font-size:10.5px;letter-spacing:.12em;text-transform:uppercase;color:var(--bg);
  background:linear-gradient(90deg,var(--accent),var(--accent-2));padding:4px 10px;border-radius:999px;font-weight:600;
}
.lab-badge .dot{width:6px;height:6px;border-radius:50%;background:var(--bg);animation:labPulse 1.6s ease-in-out infinite}
@keyframes labPulse{0%,100%{opacity:1}50%{opacity:.25}}
.lab-title{font-family:var(--font-display);font-size:19px;line-height:1.3;margin:0;color:var(--fg)}
.lab-sub{margin:0;color:var(--muted);font-size:14px}

.lab-stage{position:relative;width:100%;background:var(--code-bg);border:1px solid var(--border);border-radius:12px;overflow:hidden;margin:10px 0;touch-action:none}
.lab-stage canvas{display:block;width:100%}
.lab-stage.clickable canvas{cursor:crosshair}

.lab-controls{display:flex;flex-wrap:wrap;gap:10px 18px;align-items:center;margin:12px 0 4px}
.lab-ctl{display:flex;flex-direction:column;gap:4px;min-width:150px;flex:1 1 170px;max-width:280px}
.lab-ctl label{font-family:var(--font-mono);font-size:11px;color:var(--muted);display:flex;justify-content:space-between;gap:8px}
.lab-ctl label b{color:var(--fg);font-weight:500}
.lab-ctl input[type=range]{width:100%;accent-color:var(--accent)}
.lab-ctl select,.lab-ctl input[type=text],.lab-ctl input[type=number],.lab-ctl textarea{
  background:var(--surface-2);color:var(--fg);border:1px solid var(--border);border-radius:8px;padding:7px 9px;
  font-family:var(--font-mono);font-size:12.5px;width:100%;
}
.lab-ctl.wide{max-width:none;flex:1 1 100%}
.lab-ctl textarea{resize:vertical;min-height:54px}
.lab-btns{display:flex;flex-wrap:wrap;gap:8px}
.lab-btn{
  font-family:var(--font-body);font-weight:600;font-size:13px;cursor:pointer;
  background:var(--surface-2);border:1px solid var(--border);color:var(--fg);padding:7px 13px;border-radius:999px;
  transition:transform .12s,background .2s,border-color .2s;
}
.lab-btn:hover{border-color:var(--accent)}
.lab-btn:active{transform:scale(.96)}
.lab-btn.primary{background:var(--accent);color:#06290a;border-color:var(--accent)}
.lab-btn.on{background:var(--accent-soft);border-color:var(--accent);color:var(--fg)}
.lab-btn:disabled{opacity:.4;cursor:not-allowed}
.lab-toggle{display:inline-flex;align-items:center;gap:7px;font-size:13px;cursor:pointer;user-select:none;color:var(--fg)}
.lab-toggle input{accent-color:var(--accent);width:16px;height:16px}

.lab-readout{display:grid;grid-template-columns:repeat(auto-fill,minmax(140px,1fr));gap:8px;margin:12px 0}
.lab-stat{background:var(--surface-2);border:1px solid var(--border);border-radius:10px;padding:8px 11px}
.lab-stat .k{font-family:var(--font-mono);font-size:10.5px;color:var(--muted);text-transform:uppercase;letter-spacing:.06em}
.lab-stat .v{font-family:var(--font-mono);font-size:16px;color:var(--fg);margin-top:2px;font-variant-numeric:tabular-nums;transition:color .3s}
.lab-stat .v.good{color:var(--accent)} .lab-stat .v.warn{color:var(--warn)} .lab-stat .v.bad{color:var(--lab-bad)}

.lab-note{
  border-left:3px solid var(--accent-2);background:var(--surface-2);border-radius:0 10px 10px 0;
  padding:10px 14px;margin:12px 0;font-size:14.5px;line-height:1.55;
}
.lab-note.warn{border-left-color:var(--warn)} .lab-note.bad{border-left-color:var(--lab-bad)} .lab-note.good{border-left-color:var(--accent)}

.lab-cols{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:6px}
@media (max-width:760px){.lab-cols{grid-template-columns:1fr}}
.lab-box{background:var(--surface-2);border:1px solid var(--border);border-radius:12px;padding:12px 14px;min-width:0}
.lab-box h4{margin:0 0 8px;font-family:var(--font-mono);font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:var(--accent-2)}
.lab-math{overflow-x:auto;overflow-y:hidden;padding:2px 0}
.lab-math math{font-size:1.08em;color:var(--fg);margin:8px 0}
.lab-math .why{font-size:13px;color:var(--muted);margin:2px 0 10px}
.lab-math .why:last-child{margin-bottom:0}
math{font-family:'STIX Two Math','Cambria Math','Latin Modern Math',math}
.lab-algo{margin:0;padding-left:20px;font-size:13.5px}
.lab-algo li{margin-bottom:6px}
.lab-algo li::marker{color:var(--accent);font-family:var(--font-mono)}
.lab-algo code{font-size:12px}

/* tables used by DP / BPE labs */
.lab-scroll{overflow:auto;max-width:100%;border:1px solid var(--border);border-radius:10px;background:var(--code-bg);margin:10px 0}
.lab-grid{border-collapse:collapse;font-family:var(--font-mono);font-size:12px}
.lab-grid th,.lab-grid td{border:1px solid var(--border);padding:4px 7px;text-align:center;min-width:30px;transition:background .25s,color .25s}
.lab-grid th{color:var(--accent-2);font-weight:500;background:var(--surface-2);white-space:nowrap}
.lab-grid td.filled{color:var(--fg)}
.lab-grid td.empty{color:transparent}
.lab-grid td.cur{background:var(--accent-2);color:var(--bg)}
.lab-grid td.path{background:var(--accent);color:#06290a;font-weight:600}
.lab-align{display:flex;flex-wrap:wrap;gap:6px;margin:10px 0}
.lab-tok{display:inline-flex;flex-direction:column;align-items:center;border:1px solid var(--border);border-radius:8px;padding:4px 8px;font-family:var(--font-mono);font-size:12px;background:var(--surface-2);animation:labPop .35s ease both}
.lab-tok small{font-size:9.5px;color:var(--muted);letter-spacing:.08em}
.lab-tok.C{border-color:var(--accent)} .lab-tok.S{border-color:var(--warn);background:rgba(232,182,78,.12)}
.lab-tok.D{border-color:var(--lab-bad);background:rgba(255,107,107,.1)} .lab-tok.I{border-color:var(--lab-purple);background:rgba(183,148,255,.12)}
.lab-tok.hl{border-color:var(--accent-2);box-shadow:0 0 0 2px var(--accent-2) inset}
@keyframes labPop{from{transform:scale(.6);opacity:0}to{transform:none;opacity:1}}
.lab-chips{display:flex;flex-wrap:wrap;gap:5px;margin:6px 0}
.lab-chip{font-family:var(--font-mono);font-size:11.5px;padding:2px 8px;border-radius:999px;border:1px solid var(--border);background:var(--code-bg);animation:labPop .3s ease both}
.lab-chip.new{border-color:var(--accent);color:var(--accent)}

.ep-sub .lab-flag{color:var(--accent);margin-left:4px}

@media (prefers-reduced-motion: reduce){
  .lab-badge .dot,.lab-tok,.lab-chip{animation:none}
}

/* ================= Mascot "Chhotu" ================= */
.mascot{width:64px;height:66px;flex:0 0 auto;overflow:visible}
.mascot.tiny{width:36px;height:38px}
.mascot .m-head{fill:var(--surface-2);stroke:var(--accent);stroke-width:3}
.mascot .m-face{fill:#0b1a12}
.mascot .m-eyes ellipse{fill:#7dffb0;transform-box:fill-box;transform-origin:center;animation:mBlink 4.2s infinite}
.mascot .m-cheek{fill:#ff8fab;opacity:.75}
.mascot .m-mouth{fill:none;stroke:#7dffb0;stroke-width:3;stroke-linecap:round;transform-box:fill-box;transform-origin:center}
.mascot .m-band{fill:none;stroke:var(--accent-2);stroke-width:5;stroke-linecap:round}
.mascot .m-ear{fill:var(--accent-2)}
.mascot .m-stroke{stroke:var(--accent);stroke-width:3}
.mascot .m-ant{fill:var(--warn);animation:mGlow 1.8s ease-in-out infinite}
.mascot .m-torso{fill:var(--accent-soft);stroke:var(--accent);stroke-width:2.5}
.mascot .m-wave{fill:none;stroke:var(--accent);stroke-width:2.5;stroke-linejoin:round;stroke-linecap:round}
.mascot .m-bob{animation:mBob 3s ease-in-out infinite}
.mascot.talking .m-mouth{animation:mTalk .22s ease-in-out infinite alternate}
.mascot.talking .m-wave{animation:mWave .5s linear infinite}
@keyframes mBlink{0%,92%,100%{transform:scaleY(1)}95%{transform:scaleY(.1)}}
@keyframes mGlow{0%,100%{opacity:1}50%{opacity:.35}}
@keyframes mBob{0%,100%{transform:translateY(0)}50%{transform:translateY(-3px)}}
@keyframes mTalk{from{transform:scaleY(.4)}to{transform:scaleY(1.5)}}
@keyframes mWave{to{stroke-dashoffset:-24}}
.mascot.talking .m-wave{stroke-dasharray:6 3}

.kid-box,.ep-guide{display:flex;gap:12px;align-items:flex-start;margin:0 0 14px}
.ep-guide{margin:0 0 22px}
.kid-bubble{
  position:relative;flex:1;min-width:0;background:linear-gradient(135deg,var(--accent-soft),var(--surface-2));
  border:1px solid var(--border);border-radius:4px 14px 14px 14px;padding:10px 14px;font-size:14.5px;line-height:1.6;color:var(--fg);
}
.kid-bubble::before{content:"";position:absolute;left:-8px;top:12px;border:8px solid transparent;border-right-color:var(--border);border-left:0}
.kid-label{display:block;font-family:var(--font-mono);font-size:10.5px;letter-spacing:.08em;text-transform:uppercase;color:var(--accent);margin-bottom:3px}
.kid-text{min-height:1.6em}
.kid-text b,.ep-guide b{color:var(--accent)}
.kid-box{cursor:pointer}

/* ================= Highlighter ================= */
mark.hl{color:inherit;border-radius:3px;padding:0 1px;cursor:pointer;transition:box-shadow .3s}
mark.hl-yellow{background:rgba(255,214,10,.38)}
mark.hl-green{background:rgba(118,185,0,.38)}
mark.hl-pink{background:rgba(255,105,180,.36)}
mark.hl-blue{background:rgba(94,200,232,.38)}
mark.hl.flash{box-shadow:0 0 0 3px var(--warn);animation:labPop .4s}
.hl-pop{
  position:absolute;z-index:60;display:none;align-items:center;gap:6px;padding:6px 8px;border-radius:12px;
  background:var(--surface);border:1px solid var(--border);box-shadow:0 10px 30px rgba(0,0,0,.35)
}
.hl-pop.show{display:flex}
.hl-sw{width:24px;height:24px;border-radius:50%;border:2px solid var(--surface);cursor:pointer;box-shadow:0 0 0 1px var(--border)}
.hl-sw.hl-yellow{background:#ffd60a}.hl-sw.hl-green{background:#76b900}.hl-sw.hl-pink{background:#ff69b4}.hl-sw.hl-blue{background:#5ec8e8}
.hl-sw:hover{transform:scale(1.15)}
.hl-sep{width:1px;height:20px;background:var(--border)}
.hl-act{background:var(--surface-2);border:1px solid var(--border);color:var(--fg);border-radius:8px;padding:3px 7px;cursor:pointer;font-size:14px}
.hl-act.wide{font-size:12.5px;font-family:var(--font-body);font-weight:600}
.hl-act:hover{border-color:var(--accent)}

/* ================= Notes drawer ================= */
.study-fab{
  position:fixed;right:18px;bottom:18px;z-index:50;display:flex;align-items:center;gap:7px;
  background:var(--accent);color:#06290a;border:none;border-radius:999px;padding:11px 16px;font-family:var(--font-body);
  font-weight:700;font-size:14px;cursor:pointer;box-shadow:0 10px 30px -8px rgba(118,185,0,.6);transition:transform .2s
}
.study-fab:hover{transform:translateY(-2px)}
.study-fab.hide{opacity:0;pointer-events:none}
.fab-badge{background:#06290a;color:var(--accent);border-radius:999px;font-size:11px;padding:1px 7px;font-family:var(--font-mono)}
.study-drawer{
  position:fixed;top:0;right:0;bottom:0;z-index:70;width:min(400px,100vw);background:var(--surface);border-left:1px solid var(--border);
  display:flex;flex-direction:column;transform:translateX(105%);transition:transform .3s ease;box-shadow:-20px 0 50px rgba(0,0,0,.35)
}
.study-drawer.open{transform:none}
.nd-head{display:flex;align-items:center;gap:10px;padding:14px 16px;border-bottom:1px solid var(--border)}
.nd-head div{flex:1;display:flex;flex-direction:column}
.nd-head small{color:var(--muted);font-size:11.5px}
.nd-close{background:none;border:none;color:var(--fg);font-size:26px;cursor:pointer;line-height:1}
.nd-tabs{display:flex;gap:4px;padding:10px 12px 0;overflow-x:auto;border-bottom:1px solid var(--border)}
.nd-tab{background:none;border:none;border-bottom:2px solid transparent;color:var(--muted);padding:8px 9px;font-family:var(--font-body);font-weight:600;font-size:13px;cursor:pointer;white-space:nowrap}
.nd-tab.on{color:var(--fg);border-bottom-color:var(--accent)}
.nd-tab i{font-style:normal;font-family:var(--font-mono);font-size:10.5px;background:var(--surface-2);border-radius:999px;padding:0 6px;margin-left:3px}
.nd-body{flex:1;overflow-y:auto;padding:14px 16px}
.nd-add{display:flex;flex-direction:column;gap:8px;margin-bottom:14px}
.nd-add textarea{background:var(--surface-2);color:var(--fg);border:1px solid var(--border);border-radius:10px;padding:10px;font-family:var(--font-body);font-size:14px;resize:vertical}
.nd-add .lab-btn{align-self:flex-end}
.nd-card{background:var(--surface-2);border:1px solid var(--border);border-radius:10px;padding:10px 12px;margin-bottom:8px;animation:labPop .25s ease both}
.nd-card.done .nd-text{text-decoration:line-through;color:var(--muted)}
.nd-card.hlc{display:flex;gap:8px;align-items:flex-start;border-left-width:4px}
.nd-card.hl-yellow{border-left-color:#ffd60a}.nd-card.hl-green{border-left-color:#76b900}.nd-card.hl-pink{border-left-color:#ff69b4}.nd-card.hl-blue{border-left-color:#5ec8e8}
.nd-meta{display:flex;align-items:center;gap:8px;margin-bottom:5px}
.nd-text{font-size:14px;line-height:1.55;white-space:normal}
.nd-ep{background:var(--accent-soft);color:var(--accent);border:1px solid var(--accent);border-radius:999px;padding:3px 10px;font-family:var(--font-mono);font-size:11px;cursor:pointer;margin:4px 0 8px}
.nd-ep.small{margin:0;padding:1px 8px}
.nd-check{font-size:11.5px;color:var(--muted);display:flex;gap:4px;align-items:center}
.nd-del{margin-left:auto;background:none;border:none;color:var(--muted);font-size:18px;cursor:pointer;line-height:1}
.nd-del:hover{color:var(--lab-bad)}
.nd-jump{flex:1;text-align:left;background:none;border:none;color:var(--fg);font-family:var(--font-body);font-size:13.5px;cursor:pointer;line-height:1.5}
.nd-group{margin-bottom:12px}
.nd-empty{color:var(--muted);font-size:14px;text-align:center;padding:24px 8px}
.nd-foot{display:flex;align-items:center;justify-content:space-between;padding:12px 16px;border-top:1px solid var(--border);font-size:12px;color:var(--muted)}
.study-toast{
  position:fixed;left:50%;bottom:24px;z-index:80;transform:translate(-50%,20px);opacity:0;pointer-events:none;
  background:var(--fg);color:var(--bg);padding:10px 16px;border-radius:999px;font-size:13.5px;font-weight:600;transition:all .3s
}
.study-toast.show{opacity:1;transform:translate(-50%,0)}

/* ================= Python playground ================= */
.pg{border:1px solid var(--border);border-radius:12px;overflow:hidden;background:var(--code-bg);margin:10px 0}
.pg-bar{display:flex;flex-wrap:wrap;align-items:center;gap:8px 12px;padding:8px 10px;background:var(--surface-2);border-bottom:1px solid var(--border)}
.pg-file{font-family:var(--font-mono);font-size:12.5px;color:var(--fg)}
.pg-status{font-family:var(--font-mono);font-size:11px;color:var(--muted);flex:1;min-width:120px}
.pg-bar .lab-btns{margin-left:auto}
.pg-bar small{opacity:.7;font-size:10px;margin-left:3px}
.pg-ed{display:flex;position:relative;min-height:150px}
.pg-gutter{flex:0 0 40px;overflow:hidden;padding:13px 0;background:var(--surface);border-right:1px solid var(--border);text-align:right;user-select:none}
.pg-gutter span{display:block;padding-right:8px;font-family:var(--font-mono);font-size:12px;line-height:20.8px;color:var(--muted);opacity:.6}
.pg-gutter span.mark{color:var(--warn);opacity:1;font-weight:700}
.pg-code{position:relative;flex:1;min-width:0}
.pg-hl,.pg-ta{
  position:absolute;inset:0;margin:0;padding:13px 14px;font-family:var(--font-mono);font-size:13px;line-height:20.8px;
  white-space:pre;tab-size:4;overflow:auto;border:0;letter-spacing:0;font-variant-ligatures:none
}
.pg-hl{color:var(--fg);pointer-events:none;overflow:hidden}
.pg-hl .ln{display:block;min-width:100%;width:max-content;border-radius:3px}
.pg-hl .ln.mark{background:rgba(232,182,78,.2);box-shadow:inset 3px 0 0 var(--warn)}
.pg-hl .ln.err{background:rgba(255,107,107,.18);box-shadow:inset 3px 0 0 var(--lab-bad)}
.pg-ta{background:transparent;color:transparent;caret-color:var(--accent);resize:none;outline:none}
.pg-ta::selection{background:rgba(94,200,232,.3);color:transparent}
.pg-ta:focus{box-shadow:inset 0 0 0 2px var(--accent-soft)}
.py-k{color:#c792ea}.py-b{color:#82aaff}.py-s{color:#c3e88d}.py-c{color:#7f8c82;font-style:italic}.py-n{color:#f78c6c}
:root[data-theme="light"] .py-k{color:#7c3aed} :root[data-theme="light"] .py-b{color:#1d4ed8} :root[data-theme="light"] .py-s{color:#15803d} :root[data-theme="light"] .py-c{color:#6b7c72} :root[data-theme="light"] .py-n{color:#c2410c}
@media (prefers-color-scheme: light){
  :root:not([data-theme="dark"]) .py-k{color:#7c3aed} :root:not([data-theme="dark"]) .py-b{color:#1d4ed8} :root:not([data-theme="dark"]) .py-s{color:#15803d} :root:not([data-theme="dark"]) .py-c{color:#6b7c72} :root:not([data-theme="dark"]) .py-n{color:#c2410c}
}
.pg-out{border-top:1px solid var(--border)}
.pg-out-h{font-family:var(--font-mono);font-size:10.5px;letter-spacing:.1em;text-transform:uppercase;color:var(--accent-2);padding:8px 14px 0}
.pg-pre{margin:0;padding:8px 14px 14px;font-family:var(--font-mono);font-size:12.5px;line-height:1.6;color:var(--fg);white-space:pre-wrap;max-height:300px;overflow:auto}
.pg-pre.err{color:var(--lab-bad)}
.pg-explain{margin-top:10px}
.pg-ex{cursor:pointer;border-radius:8px;padding:4px 6px;margin-left:-6px;transition:background .2s}
.pg-ex:hover,.pg-ex.on{background:var(--accent-soft)}
.pg-lines{font-family:var(--font-mono);font-size:11px;background:var(--code-bg);color:var(--warn);border:1px solid var(--border);border-radius:6px;padding:1px 6px;cursor:pointer}

/* ================= Reading polish for the course text ================= */
.panel p,.panel li{line-height:1.7}
.panel p b,.panel li b,.callout b{color:var(--fg);background:linear-gradient(transparent 62%,var(--accent-soft) 62%);padding:0 1px}
.panel h3{display:flex;align-items:center;gap:8px}
.panel h3::before{content:"";width:8px;height:8px;border-radius:2px;background:var(--accent);flex:0 0 auto}
.bolo{box-shadow:0 6px 20px -14px var(--accent-2)}
.episode.active{animation:epIn .35s ease both}
@keyframes epIn{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}
@media (max-width:600px){.study-fab .fab-tx{display:none}.mascot{width:48px;height:50px}}
@media (prefers-reduced-motion: reduce){
  .mascot *,.episode.active{animation:none !important}
}

/* ================= shared editor (notebook + coding rounds) ================= */
.cx-ed{display:flex;position:relative;border-top:1px solid var(--border);background:var(--code-bg)}

/* ================= Code Lab notebook ================= */
.nb-bar{position:relative;display:flex;flex-wrap:wrap;gap:8px 10px;align-items:center;background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:10px 12px;margin:0 0 14px}
.nb-select{background:var(--surface-2);color:var(--fg);border:1px solid var(--border);border-radius:8px;padding:7px 9px;font-family:var(--font-body);font-weight:600;font-size:13px;max-width:240px}
.nb-bar .lab-btns{flex:1}
.nb-bar .lab-btn{padding:6px 11px;font-size:12.5px}
.nb-import{display:inline-flex;align-items:center}
.nb-status{flex-basis:100%;font-family:var(--font-mono);font-size:11px;color:var(--muted)}
.nb-cells{display:flex;flex-direction:column;gap:10px}
.nb-cell{display:flex;gap:8px;align-items:flex-start}
.nb-prompt{flex:0 0 64px;text-align:right;padding-top:10px;font-family:var(--font-mono);font-size:11.5px;color:var(--accent-2)}
.nb-cell.markdown .nb-prompt{color:var(--muted)}
.nb-main{flex:1;min-width:0;border:1px solid var(--border);border-radius:10px;overflow:hidden;background:var(--surface);transition:border-color .2s}
.nb-main:focus-within{border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-soft)}
.nb-tools{display:flex;gap:2px;justify-content:flex-end;padding:3px 6px;background:var(--surface-2)}
.nb-tools button{background:none;border:none;color:var(--muted);cursor:pointer;font-size:12.5px;padding:3px 7px;border-radius:6px;font-family:var(--font-mono)}
.nb-tools button:hover{background:var(--surface);color:var(--fg)}
.nb-tools button[data-c="run"]{color:var(--accent)}
.nb-rendered{display:none;padding:10px 16px;font-size:14.5px;line-height:1.6;cursor:text}
.nb-cell.show-md .nb-edit{display:none}
.nb-cell.show-md .nb-rendered{display:block}
.nb-rendered h2,.nb-rendered h3,.nb-rendered h4{margin:6px 0;font-family:var(--font-display)}
.nb-rendered p{margin:6px 0}
.nb-mdcode{background:var(--code-bg);padding:8px 10px;border-radius:8px;font-family:var(--font-mono);font-size:12.5px;overflow-x:auto}
.nb-empty-md{color:var(--muted);font-style:italic}
.nb-out:empty{display:none}
.nb-out{border-top:1px solid var(--border);padding:8px 12px;max-height:420px;overflow:auto}
.nb-out pre{margin:0;font-family:var(--font-mono);font-size:12.5px;line-height:1.55;white-space:pre-wrap;color:var(--fg)}
.nb-out.running pre{color:var(--muted)}
.nb-val span{color:var(--lab-bad);opacity:.85}
.nb-err{color:var(--lab-bad) !important}
.nb-fig{display:block;max-width:100%;margin:8px 0;border-radius:8px;background:#fff}
.nb-add{display:flex;gap:8px;justify-content:center;padding:6px 0 4px;margin-left:72px}
@media (max-width:600px){.nb-prompt{display:none}.nb-add{margin-left:0}}

/* ================= Test Center ================= */
.tc-h{font-family:var(--font-display);font-size:18px;margin:26px 0 12px}
.tc-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(190px,1fr));gap:10px}
.tc-card{display:flex;flex-direction:column;gap:4px;align-items:flex-start;text-align:left;background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:12px 14px;cursor:pointer;color:var(--fg);font-family:var(--font-body);transition:transform .15s,border-color .2s}
.tc-card:hover{transform:translateY(-2px);border-color:var(--accent)}
.tc-ic{font-size:22px}
.tc-card b{font-size:14px}
.tc-card small{color:var(--muted);font-family:var(--font-mono);font-size:10.5px}
.tc-best{margin-top:4px;font-family:var(--font-mono);font-size:11px;padding:2px 8px;border-radius:999px;background:var(--surface-2);color:var(--muted)}
.tc-best.good{color:var(--accent)}.tc-best.warn{color:var(--warn)}.tc-best.bad{color:var(--lab-bad)}
.tc-quiz:empty{display:none}
.tc-quiz{margin-top:16px}
.tc-head{position:relative;display:flex;flex-wrap:wrap;align-items:center;gap:10px;background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:10px 14px;margin-bottom:10px}
.tc-score{margin-left:auto;font-family:var(--font-mono);color:var(--accent)}
.tc-prog{flex-basis:100%;height:5px;background:var(--surface-2);border-radius:4px;overflow:hidden}
.tc-prog i{display:block;height:100%;width:0;background:var(--accent);transition:width .3s}
.tc-q{background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:12px 14px;margin-bottom:10px}
.tc-q p{margin:0 0 10px;font-size:15px;font-weight:600;line-height:1.5}
.tc-n{color:var(--accent);font-family:var(--font-mono);margin-right:4px}
.tc-opts{display:grid;gap:7px}
.tc-opt{text-align:left;background:var(--surface-2);border:1px solid var(--border);color:var(--fg);border-radius:10px;padding:9px 12px;cursor:pointer;font-family:var(--font-body);font-size:14px;line-height:1.45;transition:border-color .2s,background .2s}
.tc-opt:hover:not(:disabled){border-color:var(--accent-2)}
.tc-opt.right{border-color:var(--accent);background:var(--accent-soft)}
.tc-opt.wrong{border-color:var(--lab-bad);background:rgba(255,107,107,.12)}
.tc-opt:disabled{cursor:default}
.tc-exp:empty{display:none}
.tc-exp{margin-top:9px;font-size:13.5px;line-height:1.55;color:var(--fg)}
.tc-ep{margin-left:6px;background:none;border:1px solid var(--accent-2);color:var(--accent-2);border-radius:999px;padding:1px 9px;font-size:12px;cursor:pointer}
.cr-list{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:8px}
.cr-item{display:flex;flex-wrap:wrap;align-items:center;gap:4px 8px;text-align:left;background:var(--surface);border:1px solid var(--border);border-radius:10px;padding:10px 12px;cursor:pointer;color:var(--fg);font-family:var(--font-body)}
.cr-item:hover{border-color:var(--accent)}
.cr-item b{font-size:13.5px}
.cr-item small{font-family:var(--font-mono);font-size:10.5px;color:var(--muted)}
.cr-item.solved{border-color:var(--accent);background:var(--accent-soft)}
.lv{padding:1px 7px;border-radius:999px;border:1px solid var(--border)}
.lv.easy{color:var(--accent)}.lv.medium{color:var(--warn)}.lv.hard{color:var(--lab-bad)}
.cr-work:empty{display:none}
.cr-card{margin-top:14px;background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:14px}
.cr-title{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin-bottom:6px}
.cr-title b{font-family:var(--font-display);font-size:17px}
.cr-title small{font-family:var(--font-mono);font-size:11px;color:var(--muted)}
.cr-prompt{font-size:14.5px;line-height:1.6;margin:0 0 10px}
.cr-results{padding:10px 12px}
.cr-results:empty{display:none}
.cr-tests{display:grid;gap:4px;margin-bottom:8px}
.cr-t{font-size:13.5px;font-family:var(--font-body)}
.cr-t code{font-size:11.5px}
.cr-out{background:var(--code-bg);border-radius:8px;padding:8px 10px;font-family:var(--font-mono);font-size:12px;white-space:pre-wrap;margin:6px 0}

/* ================= chunking + LangGraph labs ================= */
.chunk-list{display:grid;gap:8px;margin:10px 0}
.chunk-card{border:1px solid var(--border);border-radius:10px;padding:8px 12px;background:var(--surface-2);transition:border-color .25s,box-shadow .25s}
.chunk-card.hit{border-color:var(--accent);box-shadow:0 0 0 2px var(--accent-soft)}
.chunk-meta{display:flex;align-items:center;gap:8px;font-family:var(--font-mono);font-size:11px;color:var(--muted);margin-bottom:4px}
.chunk-rank{color:var(--accent);font-weight:700}
.chunk-bar{flex:1;max-width:160px;height:6px;background:var(--code-bg);border-radius:4px;overflow:hidden;margin-left:auto}
.chunk-bar i{display:block;height:100%;background:var(--accent)}
.chunk-score{min-width:38px;text-align:right}
.chunk-text{font-size:13.5px;line-height:1.55}
.chunk-text mark.ov{background:rgba(255,214,10,.35);color:inherit;border-radius:3px}
.lg-state{margin-top:10px}
.lg-msgs{display:flex;flex-direction:column;gap:6px;max-height:280px;overflow:auto}
.lg-msg{font-size:13.5px;line-height:1.5;border-left:3px solid var(--border);padding:4px 10px;background:var(--surface);border-radius:0 8px 8px 0}
.lg-msg span{display:inline-block;min-width:56px;font-family:var(--font-mono);font-size:10.5px;text-transform:uppercase;color:var(--muted);margin-right:6px}
.lg-msg.user{border-left-color:var(--accent-2)}.lg-msg.ai{border-left-color:var(--accent)}.lg-msg.tool{border-left-color:var(--lab-purple)}.lg-msg.system,.lg-msg.human{border-left-color:var(--warn)}
.lg-msg.new{animation:labPop .35s ease}