/* ============================================================
   Java Interview Prep — study console
   Bilingual (FA/EN), dark/light, RTL-aware
   ============================================================ */
@font-face { font-family:'Vazirmatn'; src:url('./fonts/Vazirmatn-Regular.woff2') format('woff2'); font-weight:400; font-display:swap; }
@font-face { font-family:'Vazirmatn'; src:url('./fonts/Vazirmatn-Medium.woff2') format('woff2'); font-weight:500; font-display:swap; }
@font-face { font-family:'Vazirmatn'; src:url('./fonts/Vazirmatn-Bold.woff2') format('woff2'); font-weight:700; font-display:swap; }
@font-face { font-family:'InterLocal'; src:url('./fonts/Inter-400.woff2') format('woff2'); font-weight:400; font-display:swap; }
@font-face { font-family:'InterLocal'; src:url('./fonts/Inter-600.woff2') format('woff2'); font-weight:600; font-display:swap; }
@font-face { font-family:'InterLocal'; src:url('./fonts/Inter-700.woff2') format('woff2'); font-weight:700; font-display:swap; }
@font-face { font-family:'JBMono'; src:url('./fonts/JetBrainsMono-400.woff2') format('woff2'); font-weight:400; font-display:swap; }
@font-face { font-family:'JBMono'; src:url('./fonts/JetBrainsMono-600.woff2') format('woff2'); font-weight:600; font-display:swap; }

:root{
  --bg:#0b0f1a; --bg-2:#0f1524; --panel:#121a2e; --panel-2:#18223c;
  --line:#202b47; --line-2:#2b3a5f;
  --ink:#e8eefc; --ink-2:#aab6d6;
  --muted:#7d89ad;
  --gold:#fdb813; --gold-2:#ffc94b;
  --cyan:#48dfe3; --violet:#9d7bff; --green:#57d9a3; --red:#ff6b6b;
  --accent:var(--gold);
  --code-bg:#0d1322;
  --sidebar-w:320px;
  --sans-en:'InterLocal',ui-sans-serif,system-ui,-apple-system,'Segoe UI',Roboto,sans-serif;
  --sans-fa:'Vazirmatn','InterLocal',ui-sans-serif,system-ui,sans-serif;
  --mono:'JBMono',ui-monospace,'SFMono-Regular',Menlo,Consolas,monospace;
  --radius:14px;
}
:root[data-theme="light"]{
  --bg:#f6f7fb; --bg-2:#eef1f8; --panel:#ffffff; --panel-2:#f3f5fb;
  --line:#e3e7f1; --line-2:#d3d9e8;
  --ink:#16203a; --ink-2:#42506f; --muted:#6b7695;
  --code-bg:#f6f8fa;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0; background:var(--bg); color:var(--ink);
  font-family:var(--sans-en); font-size:16px; line-height:1.7;
  -webkit-font-smoothing:antialiased;
}
body[data-lang="fa"]{ font-family:var(--sans-fa); }
a{color:var(--cyan); text-decoration:none}
a:hover{text-decoration:underline}
::selection{background:var(--accent);color:#0b0f1a}
:focus-visible{outline:2px solid var(--accent);outline-offset:2px;border-radius:6px}

/* scrollbars */
*{scrollbar-width:thin;scrollbar-color:var(--line-2) transparent}
::-webkit-scrollbar{width:10px;height:10px}
::-webkit-scrollbar-thumb{background:var(--line-2);border-radius:6px;border:2px solid var(--bg)}

/* ---------- layout ---------- */
.app{display:grid;grid-template-columns:var(--sidebar-w) 1fr;min-height:100vh}
body[data-lang="fa"]{direction:rtl}
body[data-lang="en"]{direction:ltr}

/* ---------- sidebar ---------- */
.sidebar{
  position:sticky;top:0;height:100vh;overflow-y:auto;
  background:linear-gradient(180deg,var(--bg-2),var(--bg));
  border-inline-end:1px solid var(--line);
  padding:20px 14px;display:flex;flex-direction:column;gap:16px;
}
.brand{display:flex;align-items:center;gap:11px;padding:4px 8px}
.brand .mark{width:34px;height:34px;flex:0 0 auto;border-radius:9px;
  background:radial-gradient(circle at 38% 34%,#fff3ce,#fdb813 55%,#e8760b);
  box-shadow:0 0 18px 2px rgba(253,184,19,.4)}
.brand h1{font-size:15px;margin:0;line-height:1.25;font-weight:700;letter-spacing:-.01em}
.brand small{display:block;color:var(--muted);font-size:11px;font-weight:500}

.controls{display:flex;gap:8px}
.controls button{
  flex:1;display:inline-flex;align-items:center;justify-content:center;gap:6px;
  padding:8px 10px;border:1px solid var(--line-2);background:var(--panel);
  color:var(--ink-2);border-radius:10px;font:inherit;font-size:12.5px;cursor:pointer;
  transition:.15s;font-weight:600;
}
.controls button:hover{border-color:var(--accent);color:var(--ink)}
.controls button .on{color:var(--accent)}

.search{position:relative}
.search input{
  width:100%;padding:10px 12px 10px 34px;border:1px solid var(--line-2);
  background:var(--panel);color:var(--ink);border-radius:10px;font:inherit;font-size:13.5px;
}
body[data-lang="fa"] .search input{padding:10px 34px 10px 12px}
.search svg{position:absolute;inset-inline-start:10px;top:50%;transform:translateY(-50%);
  width:16px;height:16px;color:var(--muted);pointer-events:none}

.progress-mini{display:flex;align-items:center;gap:9px;padding:2px 8px;color:var(--muted);font-size:12px}
.progress-mini .bar{flex:1;height:5px;background:var(--line);border-radius:4px;overflow:hidden}
.progress-mini .bar i{display:block;height:100%;width:0;background:var(--green);transition:width .3s}

nav.toc{display:flex;flex-direction:column;gap:2px;overflow-y:auto}
.toc .group{margin-top:12px}
.toc .group-label{
  font-size:10.5px;font-weight:700;letter-spacing:.14em;text-transform:uppercase;
  color:var(--muted);padding:6px 10px 4px;
}
.toc a.item{
  display:flex;align-items:center;gap:9px;padding:7px 10px;border-radius:9px;
  color:var(--ink-2);font-size:13.5px;line-height:1.35;cursor:pointer;
  border:1px solid transparent;
}
.toc a.item:hover{background:var(--panel);color:var(--ink);text-decoration:none}
.toc a.item.active{background:var(--panel-2);color:var(--ink);border-color:var(--line-2);font-weight:600}
.toc a.item .tick{width:16px;height:16px;flex:0 0 auto;border-radius:5px;border:1.5px solid var(--line-2);
  display:grid;place-items:center;font-size:11px;color:var(--bg)}
.toc a.item.read .tick{background:var(--green);border-color:var(--green)}
.toc a.item.read .tick::after{content:'✓'}
.toc a.item .num{color:var(--muted);font-family:var(--mono);font-size:11px;min-width:20px}

/* ---------- main ---------- */
.main{min-width:0;display:flex;flex-direction:column}
.topbar{
  position:sticky;top:0;z-index:20;display:flex;align-items:center;gap:12px;
  padding:12px 20px;background:color-mix(in srgb,var(--bg) 82%,transparent);
  backdrop-filter:blur(10px);border-bottom:1px solid var(--line);
}
.topbar .hamburger{display:none;background:var(--panel);border:1px solid var(--line-2);color:var(--ink);
  width:38px;height:38px;border-radius:9px;cursor:pointer;font-size:18px}
.topbar .crumb{color:var(--muted);font-size:13px;font-family:var(--mono)}
.topbar .spacer{flex:1}
.topbar .tb-btn{border:1px solid var(--line-2);background:var(--panel);color:var(--ink-2);
  padding:8px 12px;border-radius:9px;cursor:pointer;font:inherit;font-size:12.5px;font-weight:600}
.topbar .tb-btn:hover{border-color:var(--accent);color:var(--ink)}

.reading-bar{height:3px;background:transparent}
.reading-bar i{display:block;height:100%;width:0;background:linear-gradient(90deg,var(--gold),var(--cyan))}

article.doc{max-width:920px;margin:0 auto;padding:34px 28px 90px;width:100%}
.doc .eyebrow{font-family:var(--mono);font-size:12px;letter-spacing:.12em;text-transform:uppercase;color:var(--accent)}
.doc h1.title{font-size:clamp(1.7rem,3.6vw,2.5rem);line-height:1.15;margin:.4rem 0 .5rem;font-weight:700;letter-spacing:-.02em;text-wrap:balance}
.doc .summary{color:var(--ink-2);font-size:1.05rem;margin:0 0 8px}
.doc .readtoggle{display:inline-flex;align-items:center;gap:8px;margin:14px 0 8px;padding:8px 14px;border-radius:999px;
  border:1px solid var(--line-2);background:var(--panel);color:var(--ink-2);cursor:pointer;font:inherit;font-size:13px;font-weight:600}
.doc .readtoggle.read{border-color:var(--green);color:var(--green)}
.doc hr.rule{border:0;height:1px;background:var(--line);margin:22px 0}

/* rendered markdown */
.md{font-size:16px}
.md h2{font-size:1.5rem;margin:2.2rem 0 .9rem;padding-bottom:.35rem;border-bottom:1px solid var(--line);font-weight:700;letter-spacing:-.01em}
.md h3{font-size:1.2rem;margin:1.6rem 0 .6rem;font-weight:700;color:var(--ink)}
.md h4{font-size:1.02rem;margin:1.2rem 0 .5rem;font-weight:600;color:var(--ink-2)}
.md p{margin:.7rem 0}
.md ul,.md ol{margin:.6rem 0;padding-inline-start:1.5rem}
.md li{margin:.3rem 0}
.md strong{color:var(--ink);font-weight:700}
.md a{color:var(--cyan)}
.md blockquote{margin:1rem 0;padding:.6rem 1rem;border-inline-start:3px solid var(--accent);
  background:var(--panel);border-radius:0 8px 8px 0;color:var(--ink-2)}

/* ---------- callouts (teaching layer) ---------- */
.md .callout{--co:var(--cyan);margin:1.25rem 0;border:1px solid var(--line);
  border-inline-start:4px solid var(--co);border-radius:12px;overflow:hidden;
  background:color-mix(in srgb,var(--co) 7%,var(--panel));}
.md .callout .co-h{display:flex;align-items:center;gap:.55rem;font-weight:700;color:var(--ink);
  padding:.6rem .95rem;background:color-mix(in srgb,var(--co) 13%,transparent);
  border-bottom:1px solid color-mix(in srgb,var(--co) 22%,var(--line));font-size:.96rem;letter-spacing:-.01em}
.md .callout .co-ic{font-size:1.05rem;line-height:1}
.md .callout .co-b{padding:.5rem .95rem .2rem}
.md .callout .co-b>:first-child{margin-top:.35rem}
.md .callout .co-b>:last-child{margin-bottom:.7rem}
.md .callout .co-b pre{margin:.7rem 0}
.md .co-tip{--co:var(--gold)}
.md .co-analogy{--co:var(--violet)}
.md .co-note{--co:var(--cyan)}
.md .co-key{--co:var(--green)}
.md .co-warn{--co:var(--red)}
.md .co-interview{--co:var(--gold-2)}
.md .co-summary{--co:var(--cyan)}
.md .co-summary{background:color-mix(in srgb,var(--cyan) 9%,var(--panel))}
.md :not(pre)>code{font-family:var(--mono);font-size:.86em;background:var(--panel-2);
  color:var(--gold-2);padding:.12em .4em;border-radius:6px;border:1px solid var(--line);direction:ltr;unicode-bidi:embed}
.md table{border-collapse:collapse;width:100%;margin:1rem 0;font-size:.92rem;display:block;overflow-x:auto}
.md th,.md td{border:1px solid var(--line);padding:9px 12px;text-align:start;vertical-align:top}
.md thead th{background:var(--panel-2);font-weight:700;color:var(--ink)}
.md tbody tr:nth-child(even){background:color-mix(in srgb,var(--panel) 50%,transparent)}

/* code blocks — always LTR */
.md pre{position:relative;margin:1.1rem 0;background:var(--code-bg);border:1px solid var(--line);
  border-radius:12px;overflow:hidden}
.md pre code.hljs{display:block;padding:16px 18px;overflow-x:auto;font-family:var(--mono);
  font-size:13.5px;line-height:1.6;direction:ltr;text-align:left;tab-size:2}
.md pre .copy{position:absolute;top:8px;inset-inline-end:8px;z-index:2;border:1px solid var(--line-2);
  background:color-mix(in srgb,var(--code-bg) 80%,#fff 4%);color:var(--ink-2);border-radius:7px;
  padding:4px 9px;font:inherit;font-size:11px;cursor:pointer;opacity:0;transition:.15s}
.md pre:hover .copy{opacity:1}
.md pre .copy:hover{border-color:var(--accent);color:var(--ink)}
.md pre .copy.done{color:var(--green);border-color:var(--green)}
.md pre .lang{position:absolute;top:8px;inset-inline-start:12px;font-family:var(--mono);font-size:10px;
  letter-spacing:.1em;text-transform:uppercase;color:var(--muted);pointer-events:none}
.md pre code{padding-top:26px !important}

/* prev/next */
.pager{display:flex;gap:12px;margin-top:40px;justify-content:space-between}
.pager a{flex:1;max-width:48%;padding:14px 16px;border:1px solid var(--line);border-radius:12px;
  background:var(--panel);color:var(--ink);transition:.18s}
.pager a:hover{border-color:var(--accent);text-decoration:none;transform:translateY(-2px)}
.pager a .k{display:block;font-size:11px;color:var(--muted);font-family:var(--mono);margin-bottom:3px}
.pager a.next{text-align:end}

/* home / welcome */
.home{max-width:1000px;margin:0 auto;padding:48px 28px}
.home .hero{text-align:center;padding:30px 0 10px}
.home .hero .mark{width:64px;height:64px;margin:0 auto 18px;border-radius:16px;
  background:radial-gradient(circle at 38% 34%,#fff3ce,#fdb813 55%,#e8760b);box-shadow:0 0 40px 6px rgba(253,184,19,.35)}
.home h1{font-size:clamp(2rem,5vw,3rem);margin:.2rem 0;font-weight:700;letter-spacing:-.02em}
.home .lede{color:var(--ink-2);font-size:1.15rem;max-width:60ch;margin:12px auto 0}
.home .stat-row{display:flex;flex-wrap:wrap;justify-content:center;gap:12px;margin:26px 0}
.home .stat{border:1px solid var(--line);background:var(--panel);border-radius:12px;padding:14px 20px;min-width:120px}
.home .stat b{display:block;font-size:1.6rem;color:var(--gold-2);font-weight:700}
.home .stat span{font-size:12px;color:var(--muted)}
.home .cats{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:14px;margin-top:24px}
.home .cat{border:1px solid var(--line);background:var(--panel);border-radius:14px;padding:18px 20px;transition:.18s;cursor:pointer}
.home .cat:hover{border-color:var(--accent);transform:translateY(-2px)}
.home .cat h3{margin:0 0 6px;font-size:1.05rem}
.home .cat p{margin:0;color:var(--muted);font-size:13px}
.home .cat .count{color:var(--accent);font-family:var(--mono);font-size:12px}

/* mobile */
.backdrop{display:none}
@media(max-width:960px){
  .app{grid-template-columns:1fr}
  .sidebar{position:fixed;z-index:60;inset-inline-start:0;top:0;width:min(88vw,340px);
    transform:translateX(-102%);transition:transform .25s;box-shadow:0 0 60px rgba(0,0,0,.5)}
  body[data-lang="fa"] .sidebar{transform:translateX(102%)}
  .sidebar.open,
  body[data-lang="fa"] .sidebar.open,
  body[data-lang="en"] .sidebar.open{transform:translateX(0)}
  .backdrop.show{display:block;position:fixed;inset:0;background:rgba(0,0,0,.5);z-index:55}
  .topbar .hamburger{display:grid;place-items:center}
}

/* phones — tighten spacing so reading width is generous */
@media(max-width:560px){
  body{font-size:15.5px}
  .topbar{padding:10px 14px;gap:10px}
  article.doc{padding:22px 16px 72px}
  .doc .summary{font-size:1rem}
  .md h2{font-size:1.3rem;margin:1.8rem 0 .7rem}
  .md h3{font-size:1.12rem}
  .md pre code.hljs{padding:14px 14px;font-size:.82rem}
  .md .callout .co-h{padding:.55rem .8rem}
  .md .callout .co-b{padding:.45rem .8rem .1rem}
  .md table{font-size:.88rem}
  .md th,.md td{padding:7px 10px}
}

/* print */
@media print{
  .sidebar,.topbar,.pager,.doc .readtoggle,.md pre .copy{display:none !important}
  .app{display:block}
  body{background:#fff;color:#000;font-size:12pt}
  article.doc{max-width:none;padding:0}
  .md pre{border:1px solid #ccc}
  .md pre code.hljs{color:#111;background:#f6f8fa}
}