/* Shared look for student.html and teacher.html (works offline) */
@font-face{font-family:"Vazirmatn";src:url("fonts/Vazirmatn.woff2") format("woff2");font-weight:100 900;font-display:swap}
@font-face{font-family:"JetBrains Mono";src:url("fonts/JetBrainsMono.woff2") format("woff2");font-weight:100 800;font-display:swap}

:root{
  --bg:#f6f6fb; --surface:#ffffff; --surface-2:#f0f0f8; --text:#1b1b2f; --muted:#5a5a75; --border:#e3e3ef;
  --primary:#3d6fd1; --primary-soft:#e8effc; --accent:#e8a913; --accent-soft:#fff6dc;
  --green:#12a06e; --green-soft:#e6f7f0; --yellow:#b07c00; --yellow-soft:#fff6dc; --blue:#1a86c9; --blue-soft:#e6f4fd;
  --pink:#cf3b88; --pink-soft:#fde9f3; --red:#d83a3a; --red-soft:#fdeaea;
  --shadow:0 1px 2px rgba(20,20,50,.05),0 6px 24px rgba(20,20,50,.06);
  --radius:18px;
  --code-bg:#1d1e33; --code-text:#e5e7f5;
  --font:"Vazirmatn",Tahoma,system-ui,sans-serif;
  --mono:"JetBrains Mono","Vazirmatn",Consolas,Menlo,monospace;
  --fs:18.5px;
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --bg:#0f1020; --surface:#181a2e; --surface-2:#212340; --text:#ececf7; --muted:#a9abc9; --border:#2c2e4b;
    --primary:#7aa5ff; --primary-soft:#1f2b4d; --accent:#ffcd4d; --accent-soft:#3a3120;
    --green:#3fd29c; --green-soft:#16332b; --yellow:#ffcd4d; --yellow-soft:#3a3120; --blue:#5cbaf5; --blue-soft:#17304a;
    --pink:#f17ab8; --pink-soft:#3b1d30; --red:#ff7b7b; --red-soft:#3d1c22;
    --shadow:0 1px 2px rgba(0,0,0,.3),0 8px 28px rgba(0,0,0,.35);
    --code-bg:#121326;
  }
}
:root[data-theme="dark"]{
  --bg:#0f1020; --surface:#181a2e; --surface-2:#212340; --text:#ececf7; --muted:#a9abc9; --border:#2c2e4b;
  --primary:#7aa5ff; --primary-soft:#1f2b4d; --accent:#ffcd4d; --accent-soft:#3a3120;
  --green:#3fd29c; --green-soft:#16332b; --yellow:#ffcd4d; --yellow-soft:#3a3120; --blue:#5cbaf5; --blue-soft:#17304a;
  --pink:#f17ab8; --pink-soft:#3b1d30; --red:#ff7b7b; --red-soft:#3d1c22;
  --shadow:0 1px 2px rgba(0,0,0,.3),0 8px 28px rgba(0,0,0,.35);
  --code-bg:#121326;
}
:root.big{--fs:23px}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:84px}
body{margin:0;background:var(--bg);color:var(--text);font-family:var(--font);font-size:var(--fs);line-height:1.9;-webkit-font-smoothing:antialiased}
:root[lang="en"] body{line-height:1.75}
h1,h2,h3,h4{line-height:1.35;margin:0 0 .5em}
p{margin:0 0 1em}
a{color:var(--primary)}
code,pre,.mono{font-family:var(--mono);font-variant-ligatures:none}
code{direction:ltr;unicode-bidi:isolate}
:not(pre)>code{overflow-wrap:anywhere;background:var(--surface-2);border:1px solid var(--border);padding:.05em .4em;border-radius:6px;font-size:.86em}
.wrap{max-width:1720px;margin:0 auto;padding:0 clamp(16px,3vw,48px)}
button{font:inherit;color:inherit;cursor:pointer}
[hidden]{display:none!important}

/* ---------- top nav ---------- */
.topnav{position:sticky;top:0;z-index:40;background:color-mix(in srgb,var(--bg) 88%,transparent);backdrop-filter:blur(12px);-webkit-backdrop-filter:blur(12px);border-bottom:1px solid var(--border)}
.topnav .wrap{display:flex;align-items:center;gap:12px;height:66px}
.brand{font-weight:800;font-size:19px;text-decoration:none;color:var(--text);white-space:nowrap;display:flex;align-items:center;gap:9px}
.brand .dot{width:34px;height:34px;border-radius:10px;background:linear-gradient(135deg,#3d6fd1,#f2c230);display:grid;place-items:center;font-size:18px}
.navlinks{display:flex;gap:4px;overflow-x:auto;scrollbar-width:none;flex:1}
.navlinks::-webkit-scrollbar{display:none}
.navlinks a{white-space:nowrap;text-decoration:none;color:var(--muted);font-weight:600;font-size:16px;padding:7px 13px;border-radius:999px}
.navlinks a:hover{background:var(--surface-2);color:var(--text)}
.top-btn{border:1px solid var(--border);background:var(--surface);height:40px;min-width:40px;padding:0 10px;border-radius:12px;flex:none;font-size:16px;font-weight:700}
.top-btn:hover{border-color:var(--primary)}
.top-btn.on{background:var(--primary);color:#fff;border-color:var(--primary)}
.lang-btn{color:var(--primary)}

/* ---------- hero ---------- */
.hero{padding:56px 0 30px;text-align:center}
.hero .tag{display:inline-block;background:var(--primary-soft);color:var(--primary);font-weight:700;font-size:15px;padding:6px 16px;border-radius:999px;margin-bottom:18px}
.hero h1{font-size:clamp(34px,5.5vw,64px);font-weight:900}
.hero h1 span{background:linear-gradient(90deg,#3d6fd1,#e8a913);-webkit-background-clip:text;background-clip:text;color:transparent}
.hero p.lead{font-size:21px;color:var(--muted);max-width:820px;margin:0 auto 30px}
.paths{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;text-align:start}
.path{display:block;text-decoration:none;color:var(--text);background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:22px 24px;box-shadow:var(--shadow);transition:transform .2s,border-color .2s}
.path:hover{transform:translateY(-3px);border-color:var(--primary)}
.path .ico{font-size:32px}
.path .n{font-size:14px;font-weight:700;color:var(--muted)}
.path h3{font-size:22px;margin:4px 0}
.path p{margin:0;color:var(--muted);font-size:16.5px}
.progress{max-width:760px;margin:28px auto 0;text-align:start}
.progress .bar{height:12px;background:var(--surface-2);border:1px solid var(--border);border-radius:99px;overflow:hidden}
.progress .bar div{height:100%;background:linear-gradient(90deg,#3d6fd1,#12a06e);border-radius:99px;transition:width .4s}
.progress .lbl{display:flex;justify-content:space-between;font-size:15.5px;color:var(--muted);font-weight:600;margin-bottom:6px}

/* ---------- sections ---------- */
section.part{padding:44px 0 20px}
.part-head{margin-bottom:24px}
.part-label{display:inline-block;font-size:14.5px;font-weight:800;color:var(--accent);margin-bottom:6px}
.part-head h2{font-size:clamp(28px,3.6vw,42px);font-weight:900}
.part-head p{color:var(--muted);font-size:19.5px;max-width:980px;margin:0}
.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:clamp(18px,2.4vw,38px);margin-bottom:22px}
.analogy,.example,.note,.warn{padding:12px 18px;border-radius:12px;margin:14px 0;border-inline-start:4px solid}
.analogy{background:var(--yellow-soft);border-color:var(--yellow)} .analogy b:first-child{color:var(--yellow)}
.example{background:var(--blue-soft);border-color:var(--blue)} .example b:first-child{color:var(--blue)}
.note{background:var(--green-soft);border-color:var(--green)} .note b:first-child{color:var(--green)}
.warn{background:var(--pink-soft);border-color:var(--pink)} .warn b:first-child{color:var(--pink)}
table.t{width:100%;border-collapse:collapse;font-size:.92em;margin:0 0 1em}
table.t th,table.t td{text-align:start;padding:9px 12px;border-bottom:1px solid var(--border);vertical-align:top}
table.t th{font-size:.82em;color:var(--muted);background:var(--surface-2)}
pre.code{direction:ltr;text-align:left;background:var(--code-bg);color:var(--code-text);padding:14px 18px;border-radius:12px;overflow-x:auto;font-size:15.5px;line-height:1.65;margin:0 0 1em}
.chips{display:flex;flex-wrap:wrap;gap:8px}
.chip{background:var(--surface);border:1px solid var(--border);border-radius:999px;padding:5px 14px;font-size:15px;font-weight:600}
.btn{border:1px solid var(--border);background:var(--surface);padding:9px 18px;border-radius:12px;font-weight:700;font-size:16px;transition:all .15s}
.btn:hover{border-color:var(--primary);color:var(--primary)}
.btn:disabled{opacity:.45;cursor:default}
.btn.primary{background:var(--primary);color:#fff;border-color:var(--primary)}
.btn.primary:hover{filter:brightness(1.08);color:#fff}
.btn.green{background:var(--green);color:#fff;border-color:var(--green)}
.btn.small{padding:6px 12px;font-size:14.5px;border-radius:10px}

/* ---------- explorer (sidebar + view) ---------- */
.explorer{display:grid;grid-template-columns:340px 1fr;gap:22px;align-items:start}
.explorer>*{min-width:0}
.side{position:sticky;top:84px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:14px;max-height:calc(100vh - 100px);display:flex;flex-direction:column}
.side input{width:100%;border:1px solid var(--border);background:var(--surface-2);color:var(--text);border-radius:11px;padding:10px 12px;font:inherit;font-size:16px;margin-bottom:10px;outline:none}
.side input:focus{border-color:var(--primary)}
.lesslist{overflow-y:auto;flex:1;margin:0;padding:0;padding-inline-end:10px;scrollbar-width:thin}
.lesslist h6{font-size:14px;color:var(--muted);margin:14px 6px 6px;font-weight:800}
.lesslist h6:first-child{margin-top:4px}
.lbtn{display:grid;grid-template-columns:30px 1fr auto;gap:8px;width:100%;align-items:center;text-align:start;border:0;background:transparent;padding:8px 10px;border-radius:10px;font-size:16px;line-height:1.5}
.lbtn .i{font-size:20px;text-align:center}
.lbtn .p{font-size:12.5px;color:var(--muted);font-weight:600;white-space:nowrap}
.lbtn .ok{color:var(--green);font-weight:800}
.lbtn:hover{background:var(--surface-2)}
.lbtn.on{background:var(--primary);color:#fff}
.lbtn.on .p,.lbtn.on .ok{color:#fff}
.view{min-width:0;overflow-wrap:anywhere}
.v-head{display:flex;gap:16px;align-items:center;margin-bottom:10px}
.v-head .ico{font-size:50px;line-height:1}
.v-head .meta{font-size:15px;font-weight:700;color:var(--muted);display:flex;flex-wrap:wrap;gap:8px;align-items:center}
.badge{display:inline-block;font-size:13.5px;font-weight:800;padding:2px 11px;border-radius:999px;background:var(--accent-soft);color:var(--yellow)}
.badge.blue{background:var(--blue-soft);color:var(--blue)}
.badge.green{background:var(--green-soft);color:var(--green)}
.badge.pink{background:var(--pink-soft);color:var(--pink)}
.v-head h2{font-size:clamp(26px,2.8vw,36px);margin:0;font-weight:900}
.v-short{font-size:20px;font-weight:600;background:var(--primary-soft);border-radius:12px;padding:12px 18px;margin-bottom:22px}
.sec{margin-top:30px}
.sec>h3{font-size:23px;font-weight:900;display:flex;align-items:center;gap:10px;margin-bottom:14px}
.sec>h3 .cnt{font-size:14px;color:var(--muted);font-weight:700}
.learn{max-width:1000px}
.learn ul,.learn ol{padding-inline-start:24px;margin:0 0 1em}
.learn li{margin-bottom:5px}
.words{width:auto;min-width:min(100%,560px)}
.words td:first-child{white-space:nowrap}
.v-nav{display:flex;justify-content:space-between;gap:10px;margin-top:30px;padding-top:18px;border-top:1px solid var(--border);flex-wrap:wrap}
.box{border:1px solid var(--border);border-radius:16px;padding:16px 18px;margin-bottom:16px;background:var(--surface)}
.box>h4{font-size:18.5px;margin:0 0 8px;display:flex;gap:8px;align-items:center;flex-wrap:wrap}
.box .q{font-size:1em;margin-bottom:10px}
.reveal{margin-top:10px}
.reveal>button{margin-inline-end:8px;margin-bottom:6px}
.reveal .hint{background:var(--yellow-soft);border-radius:10px;padding:10px 14px;margin-top:6px}
details.ans{margin-top:8px}
details.ans>summary{cursor:pointer;font-weight:700;color:var(--primary);list-style:none;display:inline-block;padding:4px 0}
details.ans>summary::-webkit-details-marker{display:none}
details.ans>summary::before{content:"▸ ";display:inline-block}
details.ans[open]>summary::before{content:"▾ "}
.mist li{margin-bottom:8px}

/* ---------- quiz ---------- */
.quiz .qq{border:1px solid var(--border);border-radius:14px;padding:14px 16px;margin-bottom:12px}
.quiz .qq b.n{color:var(--primary);margin-inline-end:6px}
.quiz .opts{display:grid;gap:8px;margin-top:10px}
.quiz .opt{text-align:start;border:2px solid var(--border);background:var(--surface);border-radius:12px;padding:9px 14px;font-size:.95em;line-height:1.6}
.quiz .opt:hover{border-color:var(--primary)}
.quiz .opt.right{border-color:var(--green);background:var(--green-soft)}
.quiz .opt.wrong{border-color:var(--red);background:var(--red-soft)}
.quiz .opt:disabled{cursor:default}
.quiz .why{margin-top:10px;font-size:.95em}
.quiz .score{font-weight:800;font-size:19px;margin-top:6px}

/* ---------- code editor ---------- */
.pyed{direction:ltr;border:1px solid var(--border);border-radius:14px;overflow:hidden;background:var(--code-bg);margin:8px 0 6px}
.pyed .bar{display:flex;align-items:center;gap:8px;padding:7px 10px;background:#26283f;color:#c9cbe6;font-size:14.5px;font-weight:700;flex-wrap:wrap;font-family:var(--font)}
.pyed .bar .sp{flex:1}
.pyed .bar .fig{color:#fbbf24;font-weight:700}
.pyed .mini{border:1px solid #44476a;background:#2f3150;color:#e5e7f5;border-radius:8px;padding:5px 12px;font-size:14px;font-weight:700;font-family:var(--font)}
.pyed .mini:hover{background:#3b3e63}
.pyed .mini.go{background:#3fd29c;border-color:#3fd29c;color:#06291c}
.pyed .mini.go:disabled{opacity:.6}
.pyed .ed{position:relative;background:var(--code-bg)}
.pyed .ed textarea,.pyed .ed pre{margin:0;padding:12px 14px 12px 50px;border:0;font-family:var(--mono);font-size:16.5px;line-height:1.6;tab-size:4;white-space:pre;overflow:auto;font-variant-ligatures:none;letter-spacing:0;word-spacing:0;text-align:left;direction:ltr}
.big .pyed .ed textarea,.big .pyed .ed pre{font-size:21px}
.pyed .ed pre{position:absolute;inset:0;overflow:hidden;color:var(--code-text);pointer-events:none}
.pyed .ed textarea{position:relative;display:block;width:100%;background:transparent;color:transparent;caret-color:#fff;resize:vertical;outline:none;min-height:3.6em}
.pyed .ed textarea::selection{background:rgba(122,165,255,.4);color:transparent}
.pyed .ed textarea[readonly]{caret-color:transparent}
.pyed .ln{position:absolute;top:0;left:0;width:40px;padding:12px 0;text-align:right;color:#5d6088;font-family:var(--mono);font-size:16.5px;line-height:1.6;pointer-events:none;overflow:hidden;bottom:0;white-space:pre}
.big .pyed .ln{font-size:21px}
.pyed .ln .bad{color:#ff7b7b;font-weight:800}
.pyed .out{border-top:1px solid #33354f;background:#0d0e1c;color:#e5e7f5;font-family:var(--mono);font-size:16px;line-height:1.6;padding:10px 14px;white-space:pre-wrap;word-break:break-word;unicode-bidi:plaintext;text-align:start;max-height:360px;overflow:auto;min-height:2.6em}
.big .pyed .out{font-size:20px}
.pyed .out .po-in{color:#7ee2b0}
.pyed .out .po-err{color:#ff9b9b}
.pyed .out .dim{color:#7d80a8;font-style:italic}
.pyed .err{direction:rtl;text-align:right;font-family:var(--font);background:var(--red-soft);color:var(--text);border-top:3px solid var(--red);padding:10px 16px;font-size:16.5px;line-height:1.8}
:root[lang="en"] .pyed .err{direction:ltr;text-align:left}
.pyed .err b{color:var(--red)}
.pyed .err code{font-size:.9em}
.pyed .expect{border-top:1px dashed #33354f;background:#15162a;color:#9a9dc2;font-family:var(--mono);font-size:15px;padding:8px 14px;white-space:pre-wrap;unicode-bidi:plaintext}
.pyed .expect b{font-family:var(--font);color:#c9cbe6}
.hl-k{color:#c792ea}.hl-b{color:#7dd3fc}.hl-s{color:#86efac}.hl-n{color:#fbbf24}.hl-c{color:#8a8db3;font-style:italic}.hl-f{color:#ffcb6b}.hl-o{color:#89ddff}

footer{padding:40px 0 60px;text-align:center;color:var(--muted);font-size:16px}

/* ---------- responsive ---------- */
@media (max-width:1100px){
  .explorer{grid-template-columns:1fr}
  .side{position:static;max-height:none}
  .lesslist{max-height:300px}
}
@media (max-width:720px){
  :root{--fs:17px}
  .paths{grid-template-columns:1fr}
  .v-head .ico{font-size:38px}
  .brand span:last-child{display:none}
  table.t{display:block;overflow-x:auto;max-width:100%}
  .words{min-width:0}
  .pyed .ed{overflow:hidden}
  .pyed .ed textarea,.pyed .ed pre{font-size:15px;padding-left:40px}
  .pyed .ln{width:32px;font-size:15px}
}
@media (prefers-reduced-motion: reduce){
  *{animation:none!important;transition:none!important;scroll-behavior:auto!important}
}
@media print{
  .topnav,.side,.no-print,footer{display:none!important}
  .explorer{display:block}
  body{background:#fff;color:#000}
  .card,.box{box-shadow:none;break-inside:avoid}
}