:root{
  --bg:#f6f3ff; --panel:#fff; --ink:#2b2450; --muted:#7a739c; --line:#e6e0f8;
  --accent:#7c3aed; --accent-soft:#ede7ff; --good:#16a34a; --bad:#e11d48;
  --console-bg:#241d44; --console-ink:#e9e4ff;
  --t-int:#2563eb; --t-str:#16a34a; --t-bool:#d97706; --t-float:#0891b2;
  --t-list:#7c3aed; --t-dict:#db2777; --t-func:#0284c7; --radius:16px;
  --quest-bg:#fff6e0; --quest-line:#f2c56b; --quest-ink:#5a3d0a;
}
@media (prefers-color-scheme: dark){
  :root{ --bg:#171331; --panel:#221c44; --ink:#efeaff; --muted:#a79fce; --line:#3a3167;
    --accent:#a78bfa; --accent-soft:#2e2657; --console-bg:#120e28;
    --t-int:#7ab0ff; --t-str:#5fd38a; --t-bool:#ffc25e; --t-float:#5fd0e8;
    --t-list:#c2a8ff; --t-dict:#ff8fc0; --t-func:#6fc5ff;
    --quest-bg:#2f2640; --quest-line:#7a6232; --quest-ink:#ffe1a6; }
}
*{box-sizing:border-box}
body{margin:0; background:var(--bg); color:var(--ink); font-family:"Baloo 2","Segoe UI",system-ui,sans-serif;
  background-image:radial-gradient(var(--line) 1px, transparent 1px); background-size:22px 22px}
header{display:flex; align-items:center; gap:10px; padding:12px 16px; flex-wrap:wrap}
header .logo{font-size:26px}
header h1{font-size:19px; margin:0; font-weight:800}
.nav{display:flex; gap:6px; align-items:center; margin-left:auto}
.nav select{font-family:inherit; font-weight:700; font-size:14px; padding:8px 10px; border-radius:12px;
  border:2px solid var(--line); background:var(--panel); color:var(--ink); max-width:56vw}
.nav button{padding:8px 13px; font-size:15px}
main{display:grid; grid-template-columns:minmax(0,1.05fr) minmax(0,1fr); gap:14px; padding:0 14px 20px; max-width:1220px; margin:0 auto}
@media (max-width:900px){ main{grid-template-columns:1fr} }
.card{background:var(--panel); border:2px solid var(--line); border-radius:var(--radius); overflow:hidden}
.card h2{font-size:15px; margin:0; padding:10px 14px; border-bottom:2px solid var(--line)}
.lesson{padding:12px 14px; font-size:14.5px; line-height:1.45}
.lesson b{color:var(--accent)}
.quest{display:flex; gap:8px; align-items:center; background:var(--quest-bg); color:var(--quest-ink);
  border:2px dashed var(--quest-line); border-radius:12px; padding:9px 12px; margin-bottom:10px; font-size:14.5px; line-height:1.45}
.quest .who{font-size:17px; line-height:1}
.quest b{color:inherit}
.map{display:flex; align-items:center; overflow-x:auto; padding:8px 16px 14px; max-width:1220px; margin:0 auto}
.map .mlabel{flex:0 0 auto; font-size:12.5px; font-weight:800; letter-spacing:1.5px; color:var(--muted); text-transform:uppercase; margin-right:10px}
.map .mlabel + .stop{margin-left:6px}
.map .trail{flex:1 0 10px; min-width:10px; border-top:3px dotted var(--line)}
.stop{flex:0 0 auto; position:relative; width:34px; height:34px; padding:0; font-size:14px; border-radius:50%;
  border:2px solid var(--line); background:var(--panel); color:var(--ink); transition:transform .15s}
.stop.cur{border-color:var(--accent); box-shadow:0 0 0 3px var(--accent-soft); transform:scale(1.15)}
.stop.done::after{content:"✓"; position:absolute; right:-5px; bottom:-5px; width:17px; height:17px; border-radius:50%;
  background:var(--good); color:#fff; font-size:11px; line-height:17px}
.challenge{margin-top:8px; background:var(--accent-soft); border-radius:10px; padding:8px 10px; font-size:13.5px}
.CodeMirror{height:auto; min-height:240px; font-size:15px; font-family:ui-monospace,Consolas,Menlo,monospace; background:var(--panel); color:var(--ink)}
.CodeMirror-gutters{background:var(--panel); border-right:2px solid var(--line)}
.CodeMirror-linenumber{color:var(--muted)}
.cm-s-default .cm-comment{color:var(--muted)}
.cm-s-default .cm-keyword{color:var(--accent); font-weight:700}
.cm-s-default .cm-string{color:var(--t-str)}
.cm-s-default .cm-number{color:var(--t-int)}
.cm-s-default .cm-builtin,.cm-s-default .cm-def{color:var(--t-func)}
.cm-s-default .cm-variable{color:var(--ink)}
.err-line{background:rgba(225,29,72,.16)}
.controls{display:flex; gap:10px; padding:12px 14px; border-top:2px solid var(--line); flex-wrap:wrap}
button{font-family:inherit; font-weight:800; font-size:16px; border:none; cursor:pointer; border-radius:999px; padding:10px 22px; transition:transform .1s; background:var(--accent-soft); color:var(--accent)}
button:active{transform:scale(.95)}
#runBtn{background:var(--good); color:#fff; box-shadow:0 3px 0 rgba(0,0,0,.18)}
#runBtn:disabled{background:var(--muted); cursor:wait}
.say{display:flex; gap:8px; align-items:flex-start; padding:10px 14px; font-size:14.5px}
.say .snake{font-size:22px}
.say .bubble{background:var(--accent-soft); border-radius:12px; padding:7px 12px; flex:1}
#stage-visual{min-height:210px; display:flex; flex-direction:column; align-items:center; justify-content:center; padding:10px; gap:8px}
.idle{color:var(--muted); font-size:14px; text-align:center; padding:16px}
.idle .big{font-size:42px}
.caption{font-family:ui-monospace,Consolas,monospace; font-size:13.5px; background:var(--accent-soft); padding:5px 12px; border-radius:999px; max-width:100%; overflow-wrap:anywhere}
.pointer{font-size:26px; line-height:.7; margin-bottom:-6px}
.tumbler{font-size:54px; font-weight:800; background:var(--accent-soft); border:3px dashed var(--accent); border-radius:18px; min-width:120px; text-align:center; padding:12px 20px}
.tumbler.settled{animation:pop .45s}
@keyframes pop{0%{transform:scale(.7)}60%{transform:scale(1.15)}100%{transform:scale(1)}}
/* concept explainers */
.exp{display:flex; flex-direction:column; align-items:center; gap:12px; padding:14px 10px; text-align:center; width:100%}
.exp .eh{font-size:12.5px; font-weight:800; letter-spacing:2.5px; color:var(--muted); text-transform:uppercase}
.exp .erow{display:flex; gap:10px; flex-wrap:wrap; justify-content:center; align-items:center}
.exp .ebox{border:2px solid var(--line); background:var(--panel); border-radius:14px; padding:10px 14px;
  font-family:ui-monospace,Consolas,monospace; font-size:15px; font-weight:700; min-width:80px}
.exp .ebox .sub{font-size:11.5px; color:var(--muted); font-weight:700; font-family:"Baloo 2",sans-serif; margin-top:3px}
.exp .arrow{font-size:17px; color:var(--muted); font-weight:800; font-family:ui-monospace,monospace}
.exp .enote{font-size:13.5px; color:var(--muted); max-width:430px; line-height:1.5}
.exp .big{font-size:36px}
.exp .hl{color:var(--accent)}
.exp .chip{border-radius:999px; padding:5px 13px; font-weight:800; font-size:13px; background:var(--accent-soft); color:var(--accent)}
.exp .chip.go{background:var(--good); color:#fff}
.erun{font-size:13.5px; font-weight:800; color:var(--accent)}
#vars{display:flex; flex-wrap:wrap; gap:10px; padding:12px 14px; min-height:52px}
#vars .hint{color:var(--muted); font-size:13.5px}
.vbox{border:2px solid var(--line); border-radius:12px; padding:8px 12px; animation:pop .4s; max-width:100%}
.vname{font-size:12px; color:var(--muted); font-weight:700; margin-bottom:2px}
.vval{font-family:ui-monospace,Consolas,monospace; font-size:16px; font-weight:700}
.t-int{color:var(--t-int)} .t-str{color:var(--t-str)} .t-bool{color:var(--t-bool)}
.t-float{color:var(--t-float)} .t-func{color:var(--t-func)}
.vlist{display:flex; gap:4px; flex-wrap:wrap; justify-content:center}
.vlist .cell{border:2px solid var(--t-list); border-radius:8px; padding:2px 8px; text-align:center}
.vlist .cv{font-family:ui-monospace,monospace; font-size:14px}
.vlist .ci{font-size:10.5px; color:var(--muted)}
.train{min-height:58px; align-items:center}
.train .cell{padding:5px 12px; background:var(--panel)}
.train .cv{font-size:17px; font-weight:700}
.train .cell.newcar{border-color:var(--good); animation:carIn .5s ease-out}
.train .cell{transition:opacity .25s, transform .25s, background .25s}
.train .cell.on{border-color:var(--accent); background:var(--accent-soft); transform:scale(1.18)}
.train .cell.past{opacity:.4}
.loopvar{display:flex; align-items:center; gap:8px; font-family:ui-monospace,Consolas,monospace; font-weight:700}
.loopvar .vb{border:2px solid var(--accent); border-radius:10px; padding:4px 14px; font-size:20px; min-width:48px; text-align:center}
.loopvar .vb.bump{animation:pop .35s}
.eh .ecode{text-transform:none; letter-spacing:0; font-family:ui-monospace,Consolas,monospace; font-size:14px; color:var(--accent); margin-left:6px}
.flow{display:flex; flex-direction:column; gap:10px; width:100%; max-width:460px; margin-top:4px}
.fblock{border:2px solid var(--line); border-radius:12px; padding:8px 10px; text-align:left; background:var(--panel)}
.fblock .fh{display:flex; justify-content:space-between; font-size:11.5px; font-weight:800; letter-spacing:1.5px; color:var(--muted); text-transform:uppercase; margin-bottom:4px}
.frow{display:flex; justify-content:space-between; align-items:center; gap:10px; padding:4px 8px; border-radius:8px; transition:opacity .25s, background .25s}
.frow code{font-family:ui-monospace,Consolas,monospace; font-size:14px; font-weight:700; overflow-wrap:anywhere}
.frow .tag{font-weight:800; font-size:12.5px; white-space:nowrap}
.frow.yes{background:rgba(22,163,74,.15)} .frow.yes .tag{color:var(--good)}
.frow.no{opacity:.5} .frow.no .tag{color:var(--muted)}
.frow.hit{animation:rowHit .35s}
@keyframes rowHit{0%{transform:scale(.97)}50%{transform:scale(1.02)}100%{transform:none}}
.fvals{white-space:pre-wrap; font-family:ui-monospace,Consolas,monospace; font-size:12.5px; color:var(--muted); margin-top:4px; padding:0 8px; overflow-wrap:anywhere}
.book{display:grid; grid-template-columns:minmax(0,1fr) minmax(0,1.25fr); width:100%; max-width:430px; min-height:150px;
  background:var(--quest-bg); border:2px solid var(--quest-line); border-radius:6px 14px 14px 6px; perspective:900px;
  box-shadow:4px 4px 0 var(--quest-line)}
.book .bleft{padding:8px 6px 8px 10px; display:flex; flex-direction:column; gap:4px; border-right:3px double var(--quest-line)}
.book .bright{padding:10px 12px; display:flex; flex-direction:column; justify-content:center; gap:6px; text-align:left;
  transform-origin:left center; color:var(--quest-ink)}
.book .bright.flip{animation:pageFlip .55s ease-out}
@keyframes pageFlip{0%{transform:rotateY(-95deg); opacity:.2}100%{transform:none; opacity:1}}
.dtab{font-family:ui-monospace,Consolas,monospace; font-size:12.5px; font-weight:700; text-align:left; padding:2px 8px;
  border-radius:4px 10px 10px 4px; color:var(--quest-ink); background:var(--panel); border:1.5px solid var(--quest-line);
  white-space:nowrap; overflow:hidden; text-overflow:ellipsis; transition:transform .25s, background .25s}
.dtab.on{background:var(--accent); border-color:var(--accent); color:#fff; transform:translateX(8px)}
.dtab.newtab{animation:carIn .5s ease-out}
.dword{font-family:ui-monospace,Consolas,monospace; font-size:17px; font-weight:800}
.dmean{font-family:ui-monospace,Consolas,monospace; font-size:16px; overflow-wrap:anywhere}
.dmean s{color:var(--muted)}
.dhint{font-size:12px; font-weight:800; letter-spacing:1px; text-transform:uppercase; opacity:.7}
.train .cell.ghost{border-style:dashed; border-color:var(--bad); color:var(--bad); opacity:.75; position:relative}
.train .cell.ghost .cv{text-decoration:line-through}
.train .cell.ghost .ci{color:var(--bad)}
.rnote{font-size:13px; color:var(--muted); max-width:430px; line-height:1.45}
.rnote .in{color:var(--good); font-weight:800} .rnote .out{color:var(--bad); font-weight:800}
.vlist .cell.ghost-x{border-style:dashed; border-color:var(--bad); color:var(--bad); opacity:.75}
.train .empty{border:2px dashed var(--line); border-radius:8px; padding:8px 14px; color:var(--muted); font-size:13px}
@keyframes carIn{0%{transform:translateX(40px) scale(.5); opacity:0}70%{transform:translateX(-4px) scale(1.1); opacity:1}100%{transform:none}}
.drow{display:flex; gap:8px; font-family:ui-monospace,monospace; font-size:14px; padding:1px 0}
.dk{color:var(--t-dict); font-weight:700}
.ocls{font-size:11.5px; color:var(--muted); font-family:ui-monospace,monospace}
#console{background:var(--console-bg); color:var(--console-ink); font-family:ui-monospace,Consolas,monospace; font-size:14.5px; padding:12px 14px; min-height:120px; max-height:260px; overflow-y:auto; overscroll-behavior:contain; white-space:pre-wrap; word-break:break-word; margin:0}
#console .err{color:#ff9db1}
#console .errsmall{color:#b9aee0; font-size:12.5px}
#console .user{color:#ffc25e; font-weight:700}
.cin{font-family:ui-monospace,Consolas,monospace; font-size:14.5px; background:#3a2f6b; color:#ffc25e; border:2px solid var(--accent); border-radius:8px; padding:3px 8px; width:150px; font-weight:700}
.cin:focus{outline:none}
#confetti{position:fixed; inset:0; pointer-events:none; z-index:50}
.site-foot{text-align:center; font-size:12.5px; color:var(--muted); padding:4px 16px 18px}