:root{--bg:#050907;--panel:#0c1511;--panel2:#111d17;--line:#1d2f26;--text:#e9f3ee;--muted:#9fb3a8;--accent:#2fe38a;--red:#ff5c6c;--blue:#4aa8ff;--yellow:#ffd166;--purple:#b388ff}
*{box-sizing:border-box;-webkit-tap-highlight-color:transparent}
html,body{margin:0;background:var(--bg);color:var(--text);font:16px/1.55 system-ui,-apple-system,"Segoe UI",Roboto,sans-serif}
a{color:var(--accent);text-decoration:none}
h1,h2,h3{line-height:1.2;margin:0 0 .4em}
code{background:#0a1a12;border:1px solid var(--line);border-radius:6px;padding:1px 6px;font:14px ui-monospace,Consolas,monospace;color:#9bf5c8}
.muted{color:var(--muted)}
.top{position:sticky;top:0;z-index:5;display:flex;align-items:center;gap:12px;padding:10px 14px;padding-top:calc(10px + env(safe-area-inset-top));background:rgba(5,9,7,.94);backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}
.top .ttl{flex:1;font-weight:700;font-size:17px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.logo{width:34px;height:34px;border-radius:50%}
.iconbtn{display:grid;place-items:center;width:38px;height:38px;border-radius:50%;background:var(--panel);border:1px solid var(--line);color:var(--text);font-size:18px}
.wrap{max-width:760px;margin:0 auto;padding:16px 16px 110px}
.btn{display:inline-block;border:0;border-radius:12px;background:var(--accent);color:#04120a;font-weight:700;font-size:16px;padding:12px 18px;cursor:pointer}
.btn.ghost{background:var(--panel2);color:var(--text);border:1px solid var(--line)}
.btn:disabled{opacity:.4;cursor:default}
.card{display:block;background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:14px;margin:0 0 12px;color:var(--text)}
.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:8px;margin:4px 0 8px}
.stat{background:var(--panel);border:1px solid var(--line);border-radius:14px;padding:10px;text-align:center;font-weight:600;font-size:14px}
.stat span{display:block;font-size:22px}
.meter{height:8px;background:#0a1511;border:1px solid var(--line);border-radius:99px;overflow:hidden;margin-top:8px}
.meter i{display:block;height:100%;background:var(--c,var(--accent));border-radius:99px}
.track{display:flex;gap:14px;align-items:center;border-left:4px solid var(--c,var(--accent))}
.track .ti{font-size:34px;width:54px;height:54px;display:grid;place-items:center;background:var(--panel2);border-radius:14px;flex:none}
.track h3{margin:0}.track p{margin:2px 0 0;font-size:14px}.track>div:last-child{flex:1;min-width:0}
.track.locked{opacity:.45;border-left-color:var(--line)}
h2.sec{margin:22px 0 10px;font-size:14px;text-transform:uppercase;letter-spacing:.12em;color:var(--muted)}
.lv{margin:0 0 22px}
.lv h3{display:flex;justify-content:space-between;gap:8px;align-items:baseline}
.lv.locked{opacity:.45}
.path{position:relative;margin:8px 0 0 16px;padding-left:28px;border-left:3px solid var(--line)}
.node{position:relative;display:flex;gap:12px;align-items:center;background:var(--panel);border:1px solid var(--line);border-radius:14px;padding:12px;margin:0 0 10px;color:var(--text)}
.node:before{content:"";position:absolute;left:-39px;top:50%;width:18px;height:18px;margin-top:-9px;border-radius:50%;background:var(--bg);border:3px solid var(--line)}
.node.done:before{background:var(--accent);border-color:var(--accent)}
.node.open:before{border-color:var(--accent);box-shadow:0 0 0 0 rgba(47,227,138,.7);animation:pulse 1.8s infinite}
.node.off{opacity:.45;pointer-events:none}
.node b{display:block}.node small{color:var(--muted)}.node .go{margin-left:auto;font-size:20px;color:var(--accent)}
@keyframes pulse{70%{box-shadow:0 0 0 9px rgba(47,227,138,0)}100%{box-shadow:0 0 0 0 rgba(47,227,138,0)}}
/* lesson blocks */
.lesson h1{font-size:26px}
.blk{margin:0 0 20px}
.blk h2{font-size:21px;margin-top:8px}
.callout{border-radius:14px;padding:12px 14px;border:1px solid var(--line);border-left:5px solid var(--accent);background:var(--panel)}
.callout.warn{border-left-color:var(--yellow)}.callout.law{border-left-color:var(--red)}.callout.tip{border-left-color:var(--blue)}
.callout .k{font-weight:800;text-transform:uppercase;font-size:12px;letter-spacing:.1em;display:block;margin-bottom:2px}
pre.code{background:#030806;border:1px solid var(--line);border-radius:12px;padding:12px;overflow:auto;font:14px/1.5 ui-monospace,Consolas,monospace;color:#b9ffd9}
.fig{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:10px}
.fig figcaption,.cap{color:var(--muted);font-size:14px;margin-top:6px;text-align:center}
svg.flow{width:100%;height:auto;display:block}
svg.flow text{fill:var(--text);font:700 14px system-ui,sans-serif;text-anchor:middle}
svg.flow .n,svg.flow .e{transition:opacity .35s}
svg.flow .n.dim,svg.flow .e.dim{opacity:.18}
svg.flow .n.dim ~ x{}
svg.flow line{stroke:#8aa196;stroke-width:2.2}
svg.flow .el{font:600 11px system-ui,sans-serif;fill:var(--muted);paint-order:stroke;stroke:#0c1511;stroke-width:4px}
.stepper .say{min-height:3.4em;margin:8px 2px 4px;font-size:16px}
.stepper .ctl{display:flex;gap:8px;align-items:center}
.stepper .ctl .cnt{flex:1;text-align:center;color:var(--muted);font-size:14px}
.stepper .ctl button{padding:8px 14px;font-size:15px}
.cmp{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.cmp>div{background:var(--panel);border:1px solid var(--line);border-radius:14px;padding:12px;border-top:4px solid var(--c)}
.cmp h3{font-size:16px}.cmp ul{margin:0;padding-left:18px;font-size:14px}
.terms{display:grid;gap:8px}
.term{background:var(--panel);border:1px solid var(--line);border-left:5px solid var(--c);border-radius:12px;padding:8px 12px}
.term b{color:var(--c)}
/* quizzes */
.quiz{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:14px}
.quiz .q{font-weight:700;margin-bottom:10px}
.quiz .tag{display:inline-block;font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:var(--accent);margin-bottom:4px;font-weight:800}
.opt,.chip,.mbtn{display:block;width:100%;text-align:left;background:var(--panel2);color:var(--text);border:1px solid var(--line);border-radius:12px;padding:11px 12px;margin:0 0 8px;font:inherit;cursor:pointer}
.opt.good,.mbtn.good,.ans li.good{border-color:var(--accent);background:#0d2a1c}
.opt.bad,.mbtn.bad{border-color:var(--red);background:#2a0d12}
.chips{display:flex;flex-wrap:wrap;gap:8px}.chip{width:auto;margin:0}
.ans{margin:10px 0;padding:0;list-style:none;counter-reset:s}
.ans li{counter-increment:s;background:var(--panel2);border:1px dashed var(--line);border-radius:12px;padding:9px 12px;margin:0 0 6px;cursor:pointer}
.ans li:before{content:counter(s) ". ";color:var(--accent);font-weight:800}
.mgrid{display:grid;grid-template-columns:1fr 1fr;gap:8px}
.mbtn.sel{border-color:var(--yellow);background:#2a2410}
.fb{min-height:1.4em;margin-top:6px;font-size:14px}.fb.good{color:var(--accent)}.fb.bad{color:var(--red)}
.finish{position:fixed;left:0;right:0;bottom:0;padding:12px 16px calc(12px + env(safe-area-inset-bottom));background:rgba(5,9,7,.96);border-top:1px solid var(--line);display:flex;gap:12px;align-items:center;justify-content:space-between;z-index:6}
.finish span{font-size:14px;color:var(--muted)}
.toast{position:fixed;left:50%;top:70px;transform:translateX(-50%);background:var(--accent);color:#04120a;font-weight:800;padding:10px 18px;border-radius:99px;z-index:20}
input[type=text],input[type=url],textarea{width:100%;background:var(--panel2);color:var(--text);border:1px solid var(--line);border-radius:10px;padding:10px;font:inherit}
textarea{min-height:90px;font:12px ui-monospace,Consolas,monospace}
label{display:block;margin:12px 0 4px;font-weight:600}
.row{display:flex;gap:8px;flex-wrap:wrap;margin-top:8px}
.hero{display:flex;gap:14px;align-items:center;margin:2px 0 12px}
.hero img{width:72px;height:72px;border-radius:50%;box-shadow:0 0 24px rgba(47,227,138,.35)}
.hero h1{font-size:24px;margin:0}
/* practical blocks */
.mono{font-family:ui-monospace,Consolas,monospace;font-size:14px}
.chip.good{border-color:var(--accent);background:#0d2a1c}.chip.bad{border-color:var(--red);background:#2a0d12;opacity:.7}
.buglines{background:#030806;border:1px solid var(--line);border-radius:12px;padding:6px;margin:6px 0}
.bugline{display:flex;gap:10px;width:100%;text-align:left;background:transparent;color:var(--text);border:1px solid transparent;border-radius:8px;padding:6px 8px;font:inherit;cursor:pointer;white-space:pre-wrap}
.bugline.mono{color:#b9ffd9;font-family:ui-monospace,Consolas,monospace;font-size:14px}
.bugline .ln{color:#4b6a5b;min-width:1.4em;text-align:right}
.bugline.good{border-color:var(--accent);background:#0d2a1c}.bugline.bad{border-color:var(--red);background:#2a0d12}
.blank{display:inline-block;min-width:4.5em;border-bottom:2px dashed var(--yellow);color:var(--yellow);text-align:center}.blank.good{border-bottom-color:var(--accent);color:var(--accent)}
.sim .goal{font-weight:700;margin:4px 0 8px}
.sim .hist{background:#000;border:1px solid var(--line);border-radius:10px;padding:8px 10px;max-height:300px;overflow:auto;font:13px/1.5 ui-monospace,Consolas,monospace;min-height:48px}
.sim .hist div{white-space:pre-wrap;word-break:break-word}
.sim .cmdline{color:#9bf5c8}.sim .outtxt{color:#e9f3ee;margin-bottom:6px}.sim .errtxt{color:var(--red);margin-bottom:6px}.sim .introtxt{color:var(--muted);margin-bottom:6px}
.cmdrow{display:flex;align-items:center;gap:6px;margin-top:8px;background:#000;border:1px solid var(--line);border-radius:10px;padding:2px 8px}
.cmdrow .pr{color:var(--accent);font:14px ui-monospace,Consolas,monospace;white-space:pre}
.cmdrow input.cmd{border:0;background:transparent;font:14px ui-monospace,Consolas,monospace;padding:10px 4px;color:#e9f3ee;outline:none}
.sim .row .btn{padding:8px 14px;font-size:15px}
.lab{background:var(--panel);border:1px solid var(--line);border-left:5px solid var(--yellow);border-radius:14px;padding:12px 14px}
.labrow{display:flex;gap:10px;align-items:flex-start;margin:0;padding:6px 0;font-weight:400}
.labrow input{width:20px;height:20px;margin-top:3px;accent-color:#2fe38a;flex:none}
/* code stepper */
.codestep .code.cs{background:#030806;border:1px solid var(--line);border-radius:12px;padding:6px 0;margin:8px 0;font:14px/1.6 ui-monospace,Consolas,monospace;color:#b9ffd9;overflow:auto}
.cs .cl{display:flex;gap:10px;padding:0 12px;border-left:4px solid transparent;white-space:pre}
.cs .cl.on{background:rgba(47,227,138,.16);border-left-color:var(--accent);color:#fff}
.cs .ln{color:#4b6a5b;min-width:1.4em;text-align:right;user-select:none}
.vlabel{font-size:12px;letter-spacing:.1em;text-transform:uppercase;color:var(--muted);margin-top:6px}
.vars{display:flex;flex-wrap:wrap;gap:8px;margin:6px 0;min-height:36px;align-items:center}
.var{background:var(--panel2);border:1px solid var(--line);border-radius:10px;padding:5px 12px;font:14px ui-monospace,Consolas,monospace}
.var b{color:var(--blue)}
.var.chg{border-color:var(--yellow);box-shadow:0 0 10px rgba(255,209,102,.35)}
pre.out{background:#000;border:1px solid var(--line);border-radius:10px;padding:8px 12px;margin:6px 0;color:#e9f3ee;font:14px/1.5 ui-monospace,Consolas,monospace;position:relative}
pre.out:before{content:"OUTPUT";display:block;font-size:11px;letter-spacing:.1em;color:var(--accent);margin-bottom:2px}