.cdu-app{--bg:#070a14;--panel:rgba(18,24,43,.78);--panel2:#0d1222;--sunk:#060912;--line:rgba(120,140,220,.18);--text:#e8ecff;--text2:#cdd5f5;--muted:#8a95bd;
  --a1:#7c5cff;--a2:#22d3ee;--ok:#2ee59d;--bad:#ff5d73;--warn:#ffc857;
  container-type:inline-size;position:relative;display:flex;flex-direction:column;height:min(92vh,900px);min-height:600px;
  font-family:'Space Grotesk',system-ui,sans-serif;color:var(--text);background:var(--bg);border:1px solid var(--line);border-radius:16px;
  padding:12px;max-width:1700px;margin:0 auto;box-sizing:border-box;overflow:hidden}
.cdu-app *{box-sizing:border-box}
.cdu-app button,.cdu-app select,.cdu-app input,.cdu-app textarea{font-family:inherit}
.cdu-app [hidden]{display:none!important}

/* themes: Dark · Light · Z-black · Charcoal · M-white */
.cdu-app{--hot:#ff6a00;--hot-ink:#fff;--scene-bg:#05070f}
.cdu-app[data-theme="light"]{--bg:#f3f5fc;--panel:rgba(255,255,255,.92);--panel2:#fff;--sunk:#eef1fb;--line:rgba(60,80,140,.22);--text:#161c3a;--text2:#2a3358;--muted:#5d6892;--a1:#5b6cff;--a2:#0ea5c6;--hot:#ff6a00;--scene-bg:#eef1fb}
.cdu-app[data-theme="zblack"]{--bg:#000;--panel:#0a0a0b;--panel2:#050506;--sunk:#000;--line:#1d1f22;--text:#f2f4f5;--text2:#d3d6d8;--muted:#7b8086;--a1:#00d4ff;--a2:#7dffb0;--hot:#00d4ff;--hot-ink:#001118;--scene-bg:#000}
.cdu-app[data-theme="charcoal"]{--bg:#1c1e22;--panel:#25282d;--panel2:#1f2125;--sunk:#17181b;--line:#383c43;--text:#e6e8ec;--text2:#c9ccd2;--muted:#8f96a1;--a1:#f5a524;--a2:#ff7a59;--hot:#f5a524;--hot-ink:#1c1e22;--scene-bg:#15171a}
.cdu-app[data-theme="mwhite"]{--bg:#f6f5f1;--panel:#fffefb;--panel2:#fff;--sunk:#efeee9;--line:#dcdad2;--text:#1f1f1c;--text2:#3a3a35;--muted:#85837a;--a1:#3b5bdb;--a2:#0f9d8a;--hot:#1f1f1c;--hot-ink:#fff;--scene-bg:#efeee9}
.cdu-app[data-theme="pb"]{--bg:#f5efff;--panel:rgba(255,255,255,.88);--panel2:#ffffff;--sunk:#eee5ff;--line:rgba(126,87,194,.22);--text:#29203d;--text2:#51436d;--muted:#75698d;--a1:#9b6cff;--a2:#c4a6ff;--hot:#8b5cf6;--hot-ink:#fff;--scene-bg:#eee5ff}

/* top bar */
.cdu-top{display:flex;flex-wrap:wrap;gap:10px;align-items:flex-end;justify-content:space-between;margin-bottom:10px;position:relative;z-index:1}
.cdu-brand{display:flex;align-items:center;gap:10px;font-size:21px;font-weight:700;letter-spacing:.2px;align-self:center}
.cdu-brand b{background:linear-gradient(90deg,var(--a1),var(--a2));-webkit-background-clip:text;background-clip:text;color:transparent}
.cdu-tools{display:flex;flex-wrap:wrap;gap:8px;align-items:flex-end}

.cdu-app select,.cdu-app input[type=text]{background:var(--panel2);color:var(--text);border:1px solid var(--line);border-radius:8px;padding:8px 10px;font-size:14px}
.cdu-app select{cursor:pointer;min-width:110px;max-width:100%}
.cdu-app select:focus,.cdu-app input:focus,.cdu-app textarea:focus{outline:none;border-color:var(--a1);box-shadow:0 0 0 3px color-mix(in srgb,var(--a1) 18%,transparent)}
.cdu-sel{display:flex;flex-direction:column;gap:3px;font-size:10px;letter-spacing:.1em;text-transform:uppercase;color:var(--muted)}
.cdu-sel.inline{flex-direction:row;align-items:center;gap:6px}
.cdu-sel.inline select{min-width:0;padding:3px 8px;font-size:12px}

.cdu-btn{background:var(--panel2);color:var(--text);border:1px solid var(--line);border-radius:8px;padding:8px 14px;font-size:14px;font-weight:500;cursor:pointer;transition:.15s;display:inline-flex;align-items:center;gap:8px;line-height:1.2}
.cdu-btn:hover{border-color:var(--a1)}
.cdu-btn.small{padding:6px 12px;font-size:13px}
.cdu-btn.ghost{background:transparent}
/* primary button (uses the theme accent) */
.cdu-btn.run{background:var(--hot);border:1px solid var(--hot);color:var(--hot-ink);font-weight:600;border-radius:6px;box-shadow:none}
.cdu-btn.run:hover{background:#ff8126;border-color:#ff8126}
.cdu-btn.run:active{background:#e55f00;border-color:#e55f00}
.cdu-btn:disabled{opacity:.6;cursor:wait}
.cdu-btn kbd{font:500 11px 'JetBrains Mono',monospace;background:rgba(0,0,0,.18);border-radius:4px;padding:1px 6px;color:inherit}

/* body: always side by side */
.cdu-body{--left-w:clamp(230px,27%,420px);flex:1;min-height:0;display:grid;grid-template-columns:var(--left-w) 8px minmax(0,1fr);gap:0;position:relative;z-index:1}
.cdu-left,.cdu-box{background:var(--panel);border:1px solid var(--line);border-radius:12px;min-width:0}
.cdu-left{display:flex;flex-direction:column;min-height:0;overflow:hidden;backdrop-filter:blur(8px)}
.cdu-left-head{display:flex;justify-content:space-between;align-items:center;gap:8px;padding:6px 8px;border-bottom:1px solid var(--line);flex-wrap:wrap}
.cdu-tabs{display:flex;gap:4px}
.cdu-tab{background:none;border:none;color:var(--muted);padding:7px 12px;border-radius:8px;cursor:pointer;font-size:14px;font-weight:600}
.cdu-tab:hover{color:var(--text)}
.cdu-tab.on{color:var(--text);background:color-mix(in srgb,var(--a1) 16%,transparent)}
.cdu-pane{flex:1;min-height:0;overflow:auto;padding:12px;display:flex;flex-direction:column;gap:10px}

.cdu-cat{align-self:flex-start;max-width:100%}
.cdu-q-tabs{display:flex;flex-wrap:wrap;gap:6px}
.cdu-chip{background:var(--panel2);border:1px solid var(--line);color:var(--muted);border-radius:99px;padding:4px 12px;font-size:12px;cursor:pointer;max-width:100%;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.cdu-chip.on{color:var(--text);border-color:var(--a1);background:color-mix(in srgb,var(--a1) 18%,transparent)}
.cdu-q-body{flex:1;display:flex;flex-direction:column;gap:8px;min-height:0}
.cdu-empty{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;gap:8px;color:var(--muted);padding:20px}
.cdu-empty .ico{font-size:34px;opacity:.85}
.cdu-empty p{white-space:pre-line;margin:0;font-size:14px;line-height:1.6}
.cdu-q-cat{display:inline-block;align-self:flex-start;font-size:11px;padding:2px 10px;border-radius:99px;background:color-mix(in srgb,var(--a1) 16%,transparent);color:var(--a2)}
.cdu-q-title{font-size:20px;font-weight:600;margin:2px 0 0;color:var(--text)}
.cdu-q-text{white-space:pre-wrap;line-height:1.65;font-size:14px;color:var(--text2);word-break:break-word}
.cdu-q-sample{background:var(--sunk);border:1px solid var(--line);border-radius:8px;padding:10px;font:13px 'JetBrains Mono',monospace;white-space:pre-wrap;color:var(--text)}
.cdu-q-sample-h{font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:var(--muted)}
.cdu-q-actions{display:flex;gap:6px;margin-top:auto;padding-top:8px}
.cdu-q-form{display:flex;flex-direction:column;gap:6px}
.cdu-q-form label{font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:var(--muted);margin-top:4px}
.cdu-q-form label span{text-transform:none;letter-spacing:0}
.cdu-q-form input,.cdu-q-form textarea{background:var(--panel2);color:var(--text);border:1px solid var(--line);border-radius:8px;padding:9px 11px;font-size:14px;width:100%}
.cdu-q-form textarea{resize:vertical;font-family:'JetBrains Mono',monospace;font-size:13px}
.cdu-q-form-actions{display:flex;gap:8px;margin-top:6px}

/* flowchart */
.cdu-fc-bar{display:flex;justify-content:space-between;align-items:center;font-size:12px;letter-spacing:.08em;text-transform:uppercase;color:var(--muted)}
.cdu-fc-body{flex:1;display:flex;justify-content:center;align-items:flex-start}
.cdu-fc-body svg{max-width:100%;height:auto}
.cdu-fc-hint{color:var(--muted);font-size:14px;text-align:center;line-height:1.6;padding:24px;align-self:center}
.cdu-fc-body pre{font:12px 'JetBrains Mono',monospace;white-space:pre-wrap;color:var(--text2);margin:0}

/* right side */
.cdu-main{min-width:0;min-height:0;display:flex;flex-direction:column;gap:10px}
.cdu-io{display:grid;grid-template-columns:1fr;gap:0;height:var(--io-h,230px);flex:none}
.cdu-box{overflow:hidden;display:flex;flex-direction:column;min-height:0}
.cdu-box-head{display:flex;justify-content:space-between;align-items:center;gap:8px;padding:7px 10px;border-bottom:1px solid var(--line);font-size:12px;letter-spacing:.1em;text-transform:uppercase;color:var(--muted);flex-wrap:wrap}
.cdu-meta{display:flex;align-items:center;gap:8px;text-transform:none;letter-spacing:0;flex-wrap:wrap}
.cdu-meta em{font-style:normal;font-size:12px}
.cdu-out{flex:1;min-height:0;overflow:auto;padding:10px 12px;font:13px/1.55 'JetBrains Mono',monospace;color:var(--text)}
.cdu-out pre{margin:0 0 8px;white-space:pre-wrap;word-break:break-word;font:inherit}
.cdu-out .err{color:var(--bad)}
.cdu-out .cdu-placeholder{color:var(--muted);font-family:'Space Grotesk',sans-serif}
.cdu-out[data-mode="terminal"]{background:#000;color:#3dff7a}
.cdu-out[data-mode="terminal"] .err{color:#ff6b6b}
.cdu-out[data-mode="terminal"] pre::before{content:"$ ";opacity:.5}
.cdu-out[data-mode="plain"]{background:#fff;color:#111}
.cdu-out[data-mode="plain"] .err{color:#c00}
.cdu-pill{padding:2px 10px;border-radius:99px;font-weight:600;background:rgba(46,229,157,.14);color:var(--ok)}
.cdu-pill.bad{background:rgba(255,93,115,.14);color:var(--bad)}
.cdu-link{background:none;border:none;color:var(--a2);cursor:pointer;font-size:12px;padding:0}
.cdu-link:hover{text-decoration:underline}

/* fullscreen */
.cdu-app.cdu-full{position:fixed;inset:0;z-index:999999;width:100vw;height:100vh;max-width:none;min-height:0;margin:0;border-radius:0;border:none;padding:14px}
.cdu-app.cdu-full .cdu-io{height:var(--io-h,260px)}

/* only on phone-sized containers do we stack */
@container (max-width:560px){
  .cdu-body{grid-template-columns:1fr;grid-template-rows:minmax(180px,38%) minmax(0,1fr)}
  .cdu-split{display:none}
  .cdu-io{height:var(--io-h,300px)}
}

/* algorithm tab */
.cdu-fc-btns{display:flex;gap:6px}
.cdu-al-body{display:flex;flex-direction:column;gap:2px;font-size:14px;line-height:1.5}
.cdu-al-row{display:flex;gap:8px;padding:3px 6px;border-radius:6px;color:var(--text2)}
.cdu-al-row:hover{background:color-mix(in srgb,var(--a1) 8%,transparent)}
.cdu-al-row.head{color:var(--text);font-weight:600}
.cdu-al-n{color:var(--a2);font-family:'JetBrains Mono',monospace;font-size:12px;min-width:34px;padding-top:2px;flex:none}
.cdu-al-t{word-break:break-word}

/* 3D output */
.cdu-btn.small.on{background:var(--hot);border-color:var(--hot);color:var(--hot-ink)}
.cdu-3d-wrap{position:relative;flex:1 1 auto;min-height:240px;width:100%;background:var(--scene-bg);overflow:hidden}
.cdu-3d-wrap canvas{position:absolute;inset:0;width:100%;height:100%;display:block}
.cdu-3d-ctl{position:absolute;top:8px;right:8px;display:flex;gap:6px;z-index:2}
.cdu-3d-ctl .cdu-btn{background:rgba(10,14,30,.75);color:#fff;border-color:rgba(255,255,255,.2);backdrop-filter:blur(4px)}
.cdu-3d-ctl .cdu-btn.run{background:var(--hot);border-color:var(--hot);color:var(--hot-ink)}
.cdu-app.cdu-3d .cdu-io{height:var(--io-h,max(380px,58%))}
.cdu-app.cdu-full.cdu-3d .cdu-io{height:var(--io-h,max(380px,58%))}


/* ===== v1.5 additions ===== */
.cdu-run-grp{display:flex;gap:8px;align-items:center}

/* flowchart legend + zoom */
.cdu-legend{display:flex;flex-wrap:wrap;gap:6px}
.cdu-legend .lg{font-size:11px;font-weight:600;padding:2px 9px;border-radius:99px;color:#fff;border:1.5px solid}
.lg.st{background:#16a34a;border-color:#86efac}.lg.en{background:#dc2626;border-color:#fca5a5}
.lg.io{background:#0369a1;border-color:#7dd3fc}.lg.pr{background:#0f766e;border-color:#5eead4}
.lg.pc{background:#4338ca;border-color:#a5b4fc}.lg.dc{background:#b45309;border-color:#fcd34d}
.lg.lp{background:#7e22ce;border-color:#d8b4fe}.lg.cl{background:#475569;border-color:#cbd5e1}
.lg.sp{background:#be123c;border-color:#fda4af}
.cdu-fc-body{justify-content:flex-start;overflow:auto}
.cdu-fc-body svg{max-width:none!important;margin:0 auto;flex:none}

/* algorithm */
.cdu-al-sum{display:flex;flex-direction:column;gap:8px;padding:10px;border:1px solid var(--line);border-radius:12px;background:linear-gradient(135deg,color-mix(in srgb,var(--a1) 12%,transparent),rgba(34,211,238,.08))}
.cdu-al-chips{display:flex;flex-wrap:wrap;gap:6px}
.cdu-al-chip{font-size:12px;font-weight:600;padding:3px 10px;border-radius:99px;background:var(--panel2);border:1px solid var(--line);color:var(--text)}
.cdu-al-cx{font-size:13px;color:var(--text2)}
.cdu-al-cx b{font-family:'JetBrains Mono',monospace;font-size:15px;color:var(--hot)}
.cdu-al-vars{display:flex;flex-wrap:wrap;gap:5px;align-items:center;font-size:12px;color:var(--muted)}
.cdu-al-vars code{font:600 12px 'JetBrains Mono',monospace;padding:1px 7px;border-radius:6px;background:rgba(129,140,248,.18);color:#a5b4fc}
.cdu-al-row{display:flex;gap:8px;align-items:flex-start;padding:6px 8px;border-radius:8px;color:var(--text2);border-left:4px solid var(--kc,#888);background:var(--panel2);margin-bottom:2px}
.cdu-al-row:hover{filter:brightness(1.12)}
.cdu-al-row .ic{flex:none;width:22px;text-align:center}
.cdu-al-n{color:var(--muted);font-family:'JetBrains Mono',monospace;font-size:11px;min-width:34px;padding-top:3px;flex:none}
.cdu-al-t{flex:1;word-break:break-word}
.cdu-al-row.head{cursor:pointer;color:var(--text);font-weight:600}
.cdu-al-row .arr{flex:none;color:var(--muted);font-size:11px;padding-top:3px}
.cdu-al-row.k-start,.cdu-al-row.k-end{--kc:#4ade80}.cdu-al-row.k-end{--kc:#f87171}
.cdu-al-row.k-in{--kc:#38bdf8}.cdu-al-row.k-out{--kc:#2dd4bf}.cdu-al-row.k-set{--kc:#818cf8}
.cdu-al-row.k-if{--kc:#fbbf24}.cdu-al-row.k-loop{--kc:#c084fc}.cdu-al-row.k-call{--kc:#94a3b8}
.cdu-al-row.k-stop{--kc:#fb7185}.cdu-al-row.k-case{--kc:#22d3ee}
.cdu-al-body{display:flex;flex-direction:column}

/* debugger */
.cdu-dbg-main{display:flex;flex-direction:column;gap:8px}
.cdu-dbg-ctl{display:flex;gap:6px;flex-wrap:wrap;align-items:center}
.cdu-dbg-ctl select{min-width:0;padding:6px 8px;font-size:12px}
.cdu-dbg-slider{width:100%;accent-color:var(--hot)}
.cdu-dbg-info{display:flex;justify-content:space-between;font-size:13px;color:var(--text2)}
.cdu-dbg-info span{color:var(--hot);font-weight:600;font-family:'JetBrains Mono',monospace}
.cdu-dbg-h{font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:var(--muted);margin-top:4px}
.cdu-dbg-h small{text-transform:none;letter-spacing:0;color:var(--a2)}
.cdu-dbg-vars{display:grid;grid-template-columns:auto 1fr;gap:3px 10px;font:13px 'JetBrains Mono',monospace;background:var(--sunk);border:1px solid var(--line);border-radius:10px;padding:8px 10px;min-height:44px}
.cdu-dbg-vars .nm{color:#a5b4fc}
.cdu-dbg-vars .vl{color:var(--text);word-break:break-all}
.cdu-dbg-vars .chg{background:color-mix(in srgb,var(--hot) 22%,transparent);border-radius:4px;padding:0 4px;color:#ffb066}
.cdu-dbg-vars .none{grid-column:1/-1;color:var(--muted);font-family:'Space Grotesk',sans-serif}
.cdu-dbg-out{margin:0;white-space:pre-wrap;word-break:break-word;font:13px 'JetBrains Mono',monospace;background:var(--sunk);border:1px solid var(--line);border-radius:10px;padding:8px 10px;min-height:44px;color:var(--text)}
.cdu-dbg-err{color:var(--bad);font:13px 'JetBrains Mono',monospace;background:rgba(255,93,115,.1);border:1px solid rgba(255,93,115,.4);border-radius:10px;padding:8px 10px;white-space:pre-wrap}
.cdu-dbg-line{background:color-mix(in srgb,var(--hot) 22%,transparent)!important}
.cdu-dbg-bar{border-left:4px solid var(--hot)!important;margin-left:3px}

/* question: solved + actions */
.cdu-q-solved{display:inline-block;align-self:flex-start;font-size:11px;font-weight:700;padding:2px 10px;border-radius:99px;background:rgba(46,229,157,.15);color:var(--ok)}
.cdu-q-meta{display:flex;gap:6px;flex-wrap:wrap}
.cdu-q-filter-row{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:8px}.cdu-q-filter-row .cdu-cat{min-width:140px}
.cdu-q-difficulty{display:inline-block;align-self:flex-start;font-size:11px;font-weight:700;padding:2px 10px;border-radius:99px;background:color-mix(in srgb,var(--hot) 15%,transparent);color:var(--hot)}
.cdu-q-difficulty.diff-easy{--d:#16a34a;color:#15803d;background:rgba(22,163,74,.12)}
.cdu-q-difficulty.diff-hard{--d:#d97706;color:#b45309;background:rgba(217,119,6,.12)}
.cdu-q-difficulty.diff-super-hard{--d:#dc2626;color:#b91c1c;background:rgba(220,38,38,.12)}

/* progress modal + toast */
.cdu-toast{position:absolute;left:50%;bottom:18px;transform:translateX(-50%);z-index:30;background:var(--panel2);color:var(--text);border:1px solid var(--hot);border-radius:99px;padding:10px 18px;font-size:14px;font-weight:600;box-shadow:0 10px 30px rgba(0,0,0,.4);animation:cduToast .3s ease}
@keyframes cduToast{from{opacity:0;transform:translate(-50%,12px)}to{opacity:1;transform:translate(-50%,0)}}

/* ===== v1.6: algorithm as a flow (boxes + arrows, like the Algorithmic Analysis diagram) ===== */
.cdu-al-body.cdu-af-wrap,.cdu-al-body{display:block}
.cdu-af{display:flex;justify-content:center;padding:6px 4px 18px}
.cdu-af-list{display:flex;flex-direction:column;align-items:center;gap:0;width:100%}
.cdu-af-item{display:flex;flex-direction:column;align-items:center;position:relative;max-width:100%}
.cdu-af-branch{display:flex;flex-direction:column;align-items:center;position:relative;max-width:100%}
.cdu-af-arrow{position:relative;width:2px;height:24px;background:var(--muted);flex:none;margin:0 auto}
.cdu-af-arrow::after{content:"";position:absolute;left:50%;bottom:-1px;transform:translateX(-50%);border:6px solid transparent;border-top:8px solid var(--muted);border-bottom:0}
.cdu-af-lab{position:absolute;left:8px;top:50%;transform:translateY(-50%);font-size:11px;font-weight:700;color:var(--text);background:var(--panel);border:1px solid var(--line);border-radius:99px;padding:0 7px;line-height:17px}

.cdu-af-node{--kc:#818cf8;position:relative;min-width:170px;max-width:100%;padding:10px 16px;text-align:center;font-size:14px;line-height:1.35;font-weight:600;color:var(--text);
  background:color-mix(in srgb,var(--kc) 24%,var(--panel2));border:2px solid var(--kc);border-radius:6px;box-shadow:0 4px 14px color-mix(in srgb,var(--kc) 18%,transparent);word-break:break-word}
.cdu-af-no{position:absolute;top:-9px;left:-9px;min-width:22px;height:18px;padding:0 5px;border-radius:99px;background:var(--kc);color:#fff;font:700 10px/18px 'JetBrains Mono',monospace;text-align:center}
.cdu-af-node:hover{filter:brightness(1.1)}
.cdu-af-node.k-start,.cdu-af-node.k-end{border-radius:99px;min-width:120px}
.cdu-af-node.k-start{--kc:#22c55e}.cdu-af-node.k-end{--kc:#ef4444}
.cdu-af-node.k-in{--kc:#38bdf8;transform:skewX(-10deg)}.cdu-af-node.k-out{--kc:#2dd4bf;transform:skewX(-10deg)}
.cdu-af-node.k-in .cdu-af-txt,.cdu-af-node.k-out .cdu-af-txt{display:inline-block;transform:skewX(10deg)}
.cdu-af-node.k-in .cdu-af-no,.cdu-af-node.k-out .cdu-af-no{transform:skewX(10deg)}
.cdu-af-node.k-set{--kc:#6366f1}.cdu-af-node.k-call{--kc:#94a3b8}.cdu-af-node.k-stop{--kc:#fb7185}.cdu-af-node.k-case{--kc:#22d3ee}
/* decisions & loops: diamonds */
.cdu-af-node.k-if,.cdu-af-node.k-loop{--kc:#f59e0b;background:none;border:none;box-shadow:none;padding:26px 46px;min-width:210px;isolation:isolate}
.cdu-af-node.k-loop{--kc:#a855f7}
.cdu-af-node.k-if::before,.cdu-af-node.k-loop::before,.cdu-af-node.k-if::after,.cdu-af-node.k-loop::after{content:"";position:absolute;z-index:-1;clip-path:polygon(50% 0,100% 50%,50% 100%,0 50%)}
.cdu-af-node.k-if::before,.cdu-af-node.k-loop::before{inset:0;background:var(--kc)}
.cdu-af-node.k-if::after,.cdu-af-node.k-loop::after{inset:2.5px;background:color-mix(in srgb,var(--kc) 24%,var(--panel2))}
.cdu-af-node.k-if .cdu-af-no,.cdu-af-node.k-loop .cdu-af-no{top:4px;left:calc(50% - 11px)}

/* loop feedback arrow (the "No -> go back" line in the reference): grid so it lines up with the diamond's centre */
.cdu-af-item.loopitem{display:grid;grid-template-columns:auto 28px;grid-template-rows:auto auto;margin-left:28px;align-items:stretch}
.cdu-af-item.loopitem>.cdu-af-node{grid-column:1;grid-row:1;justify-self:center}
.cdu-af-item.loopitem>.cdu-af-branch{grid-column:1;grid-row:2;justify-self:stretch;padding-bottom:26px}
.cdu-af-bka{grid-column:2;grid-row:1;display:flex;flex-direction:column;justify-content:flex-end}
.cdu-af-bka>i{display:block;height:50%;border-right:2px solid #a855f7;position:relative;margin-right:0}
.cdu-af-bka>i::before{content:"";position:absolute;left:-2px;top:-6px;border:6px solid transparent;border-right:9px solid #a855f7;border-left:0;transform:translateY(-1px)}
.cdu-af-bka>i::after{content:"";position:absolute;left:0;top:-1px;width:100%;border-top:2px solid #a855f7}
.cdu-af-bkb{grid-column:2;grid-row:2;border-right:2px solid #a855f7;border-bottom:2px solid #a855f7;border-radius:0 0 12px 0;margin-bottom:24px}
.cdu-af-branch.loop{position:relative}
.cdu-af-branch.loop::after{content:"";position:absolute;left:50%;right:-28px;bottom:24px;border-top:2px solid #a855f7}
.cdu-af-branch.loop::before{content:"";position:absolute;left:50%;bottom:24px;width:2px;height:12px;background:#a855f7;transform:translateX(-1px)}
.cdu-af-back{position:absolute;left:50%;bottom:2px;transform:translateX(-50%);font-size:11px;color:#a855f7;font-weight:700;letter-spacing:.02em;white-space:nowrap}
.cdu-af-node.k-else{--kc:#f59e0b;min-width:140px;border-style:dashed}
.cdu-af-branch .cdu-af-list{position:relative}
@media (prefers-reduced-motion:no-preference){.cdu-af-node{animation:cduAfIn .35s ease both}}
@keyframes cduAfIn{from{opacity:0;translate:0 6px}to{opacity:1;translate:0 0}}

/* ================= Learning Coach ================= */
.cdu-error-card{margin-top:10px;padding:14px 16px;border:1px solid color-mix(in srgb,var(--bad) 38%,var(--line));border-radius:12px;background:color-mix(in srgb,var(--bad) 7%,var(--panel2));color:var(--text)}
.cdu-error-card-head{display:flex;justify-content:space-between;align-items:center;font-weight:700;margin-bottom:10px}
.cdu-error-section{margin:7px 0;line-height:1.55}.cdu-error-section b{color:var(--text)}
.cdu-error-fix{margin-top:10px;padding:10px 12px;border-radius:9px;background:color-mix(in srgb,var(--ok) 9%,var(--panel2));border:1px solid color-mix(in srgb,var(--ok) 28%,var(--line));line-height:1.55}
.cdu-line-link{cursor:pointer}.cdu-line-link:hover{filter:brightness(1.18)}
.cdu-af-node[data-line], .cdu-af-node[data-line] *{cursor:pointer}
.cdu-af-node.is-linked{outline:2px solid var(--hot);box-shadow:0 0 0 4px color-mix(in srgb,var(--hot) 14%,transparent)}
.cdu-fc-node-linked{cursor:pointer}
.cdu-fc-node-linked.is-linked{filter:drop-shadow(0 0 7px var(--hot))}
.cdu-array-title{margin-top:12px}.cdu-array-row{display:flex;gap:5px;overflow:auto;padding:6px 0 8px}
.cdu-array-cell{min-width:48px;padding:6px 7px;border:1px solid var(--line);border-radius:7px;background:var(--panel2);text-align:center;font:12px 'JetBrains Mono',monospace}
.cdu-array-cell .idx{display:block;font-size:9px;color:var(--muted);margin-bottom:3px}.cdu-array-cell.chg{border-color:var(--hot);box-shadow:0 0 0 2px color-mix(in srgb,var(--hot) 13%,transparent)}
.cdu-coach{margin-top:10px;padding:10px 12px;border:1px solid color-mix(in srgb,var(--warn) 32%,var(--line));border-radius:9px;background:color-mix(in srgb,var(--warn) 7%,var(--panel2));line-height:1.5}

/* ===== v1.9: resizable layout, file list, input bar, big 3D ===== */
.cdu-left{margin-right:0}
.cdu-split{cursor:col-resize;position:relative;touch-action:none}
.cdu-split::after{content:"";position:absolute;top:0;bottom:0;left:3px;width:2px;border-radius:2px;background:var(--line);transition:.15s}
.cdu-split:hover::after,.cdu-split.on::after{background:var(--hot);width:3px;left:2.5px}
.cdu-vsplit{height:10px;flex:none;cursor:row-resize;position:relative;touch-action:none}
.cdu-vsplit::after{content:"";position:absolute;left:0;right:0;top:4px;height:2px;border-radius:2px;background:var(--line);transition:.15s}
.cdu-vsplit:hover::after,.cdu-vsplit.on::after{background:var(--hot);height:3px;top:3.5px}
.cdu-app.cdu-left-off .cdu-body{grid-template-columns:0 0 minmax(0,1fr)}
.cdu-app.cdu-left-off .cdu-left{visibility:hidden;border:0}
.cdu-app.cdu-left-off .cdu-split{visibility:hidden}
.cdu-app.cdu-left-off #cdu-panel-toggle{background:var(--hot);border-color:var(--hot);color:var(--hot-ink)}

.cdu-files{display:flex;flex-direction:column;gap:3px;margin:6px 0 10px}
.cdu-file{display:flex;align-items:center;gap:8px;width:100%;text-align:left;background:transparent;border:1px solid transparent;color:var(--text2);border-radius:8px;padding:6px 9px;font-size:13px;cursor:pointer}
.cdu-file:hover{background:color-mix(in srgb,var(--a1) 9%,transparent)}
.cdu-file.on{background:color-mix(in srgb,var(--hot) 14%,transparent);border-color:color-mix(in srgb,var(--hot) 55%,transparent);color:var(--text)}
.cdu-file .ico{flex:none}
.cdu-file .nm{flex:1;min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.cdu-file .df{flex:none;font-size:10px;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}

.cdu-inbar{padding:10px 12px;border-bottom:1px solid var(--line);background:color-mix(in srgb,var(--hot) 8%,var(--panel));display:flex;flex-direction:column;gap:8px}
.cdu-inbar-t{font-size:13px;color:var(--text)}
.cdu-inbar textarea{width:100%;background:var(--sunk);color:var(--text);border:1px solid var(--line);border-radius:8px;padding:8px 10px;font:13px/1.5 'JetBrains Mono',monospace;resize:vertical;min-height:54px;max-height:160px}
.cdu-inbar-a{display:flex;gap:8px}
.cdu-app .cdu-box-head .cdu-run-grp{margin-left:6px}

.cdu-app.cdu-3dx .cdu-editor-wrap,.cdu-app.cdu-3dx .cdu-vsplit{display:none}
.cdu-app.cdu-3dx .cdu-io{flex:1 1 auto;height:auto;min-height:0}

/* ===== v1.9.1: flowchart / algorithm usability ===== */
.cdu-tabs{flex-wrap:wrap;gap:2px}
.cdu-tab{padding:6px 10px;font-size:13px;white-space:nowrap}
.cdu-body.cdu-wide-left:not(.cdu-custom-w){--left-w:clamp(340px,46%,680px)}
.cdu-app .cdu-coach{font-size:12px!important;line-height:1.45;padding:8px 10px!important}
.cdu-fc-bar{flex-wrap:wrap}

/* ===== v2.0 Save Code + mobile navigation ===== */
.cdu-savedbar{border:1px solid var(--line);border-radius:12px;background:var(--panel);overflow:hidden;flex:0 0 auto;max-height:190px}
.cdu-savedbar-left{margin:8px 10px;max-height:220px}
.cdu-saved-head{display:flex;justify-content:space-between;align-items:center;padding:7px 10px;border-bottom:1px solid var(--line);font-size:12px;color:var(--text2)}
.cdu-saved-list{display:flex;gap:7px;overflow:auto;padding:8px}.cdu-saved-item{display:flex;align-items:center;gap:6px;min-width:180px;padding:7px 9px;border:1px solid var(--line);border-radius:8px;background:var(--panel2)}
.cdu-saved-item b{font-size:12px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;max-width:130px}.cdu-saved-item small{color:var(--muted);font-size:9px}
.cdu-saved-item button{border:0;background:transparent;color:var(--a2);cursor:pointer;font-size:11px}
@container (max-width:760px){
  .cdu-top{align-items:stretch}.cdu-brand{font-size:17px}.cdu-tools{width:100%;display:grid;grid-template-columns:repeat(2,minmax(0,1fr))}
  .cdu-tools .cdu-sel{min-width:0}.cdu-tools .cdu-btn{justify-content:center}
  .cdu-left-head{overflow:hidden}.cdu-tabs{width:100%;overflow-x:auto;scrollbar-width:none;padding-bottom:2px}.cdu-tabs::-webkit-scrollbar{display:none}.cdu-tab{white-space:nowrap;flex:none;padding:7px 10px;font-size:12px}
  .cdu-body{grid-template-columns:1fr}.cdu-left{min-height:250px}.cdu-main{min-height:430px}.cdu-editor-wrap{min-height:260px}
  .cdu-split,.cdu-vsplit{touch-action:none}.cdu-io{height:300px!important}
  .cdu-box-head{position:relative}.cdu-meta{gap:5px}.cdu-run-grp{width:100%;display:grid;grid-template-columns:1fr 1.2fr}.cdu-run-grp .cdu-btn{justify-content:center}
}
@container (max-width:560px){
  .cdu-app{height:auto;min-height:calc(100vh - 12px);padding:7px;border-radius:10px}
  .cdu-top{gap:6px;margin-bottom:7px}.cdu-brand{width:100%;justify-content:center}
  .cdu-tools{grid-template-columns:1fr 1fr;gap:5px}.cdu-tools .cdu-sel:nth-child(3){display:none}
  .cdu-body{display:flex;flex-direction:column;gap:7px}.cdu-left{order:1;min-height:245px;max-height:43vh}.cdu-main{order:2;min-height:520px}
  .cdu-pane{padding:9px}.cdu-left-head{padding:4px}.cdu-q-actions{flex-wrap:wrap}.cdu-q-actions .cdu-btn{flex:1}
  .cdu-editor-wrap{min-height:290px}.cdu-io{height:310px!important}.cdu-box-head{padding:6px 8px}
  .cdu-savedbar{max-height:150px}.cdu-saved-item{min-width:150px}
}