:root{
  --bg:#ffffff; --bg-alt:#f6f7f9; --bg-code:#f3f4f6; --fg:#1f2430; --fg-muted:#5b6472;
  --heading:#0b1220; --border:#e3e6ea; --accent:#1d4ed8; --accent-soft:#eaf0ff;
  --sidebar:#fbfbfc; --shadow:0 1px 2px rgba(16,24,40,.06);
  --mono:ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,"Liberation Mono",monospace;
  --sans:system-ui,-apple-system,"Segoe UI",Roboto,"Noto Sans Bengali","Helvetica Neue",Arial,sans-serif;
}
@media (prefers-color-scheme:dark){
  :root:not([data-theme="light"]){
    --bg:#0e1117; --bg-alt:#161b22; --bg-code:#161b22; --fg:#c9d1d9; --fg-muted:#8b949e;
    --heading:#f0f6fc; --border:#272e37; --accent:#6ea8fe; --accent-soft:#17233b;
    --sidebar:#0b0e14; --shadow:none;
  }
}
:root[data-theme="dark"]{
  --bg:#0e1117; --bg-alt:#161b22; --bg-code:#161b22; --fg:#c9d1d9; --fg-muted:#8b949e;
  --heading:#f0f6fc; --border:#272e37; --accent:#6ea8fe; --accent-soft:#17233b;
  --sidebar:#0b0e14; --shadow:none;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:72px}
body{margin:0;background:var(--bg);color:var(--fg);font-family:var(--sans);
     font-size:16px;line-height:1.7;-webkit-text-size-adjust:100%}
a{color:var(--accent);text-decoration:none}
a:hover{text-decoration:underline}
.topbar{position:sticky;top:0;z-index:30;display:flex;align-items:center;gap:12px;
  height:56px;padding:0 16px;background:var(--bg);border-bottom:1px solid var(--border)}
.brand{display:flex;align-items:center;gap:9px;font-weight:700;color:var(--heading);letter-spacing:-.01em}
.brand .mark{display:grid;place-items:center;width:26px;height:26px;border-radius:7px;
  background:var(--accent);color:#fff;font-size:13px;font-weight:800}
.brand small{display:block;font-weight:500;font-size:11px;color:var(--fg-muted);letter-spacing:0}
.topbar .spacer{flex:1}
.btn{display:inline-grid;place-items:center;width:34px;height:34px;border:1px solid var(--border);
  border-radius:8px;background:var(--bg-alt);color:var(--fg);cursor:pointer;font-size:14px}
.btn:hover{border-color:var(--accent);color:var(--accent)}
#navToggle{display:none}
.layout{display:grid;grid-template-columns:286px minmax(0,1fr);gap:0;max-width:1400px;margin:0 auto}
.sidebar{border-right:1px solid var(--border);background:var(--sidebar);
  position:sticky;top:56px;height:calc(100vh - 56px);overflow-y:auto;padding:18px 10px 48px}
.filter{width:100%;padding:8px 10px;margin:0 0 14px;border:1px solid var(--border);border-radius:8px;
  background:var(--bg);color:var(--fg);font:inherit;font-size:13.5px}
.navgroup{margin:0 0 6px;padding:10px 10px 4px;font-size:11px;font-weight:700;letter-spacing:.07em;
  text-transform:uppercase;color:var(--fg-muted)}
.sidebar a{display:block;padding:6px 10px;border-radius:7px;color:var(--fg);font-size:14px;line-height:1.45}
.sidebar a:hover{background:var(--bg-alt);text-decoration:none}
.sidebar a.active{background:var(--accent-soft);color:var(--accent);font-weight:600}
.content{min-width:0;padding:34px 40px 80px;max-width:62rem}
.content h1{font-size:2rem;line-height:1.25;color:var(--heading);margin:.2em 0 .6em;letter-spacing:-.02em}
.content h2{font-size:1.4rem;line-height:1.3;color:var(--heading);margin:2.2em 0 .5em;
  padding-bottom:.3em;border-bottom:1px solid var(--border)}
.content h3{font-size:1.12rem;color:var(--heading);margin:1.8em 0 .4em}
.content h4{font-size:1rem;color:var(--heading);margin:1.5em 0 .3em}
.content p,.content li{overflow-wrap:break-word}
.content ul,.content ol{padding-left:1.4em}
.content li{margin:.25em 0}
.content code{font-family:var(--mono);font-size:.875em;background:var(--bg-code);
  border:1px solid var(--border);border-radius:5px;padding:.12em .36em}
.content pre{background:var(--bg-code);border:1px solid var(--border);border-radius:10px;
  padding:14px 16px;overflow-x:auto;font-size:13px;line-height:1.55;box-shadow:var(--shadow)}
.content pre code{background:none;border:0;padding:0;font-size:inherit}
.table-wrap{overflow-x:auto;margin:1.2em 0;border:1px solid var(--border);border-radius:10px}
.content table{border-collapse:collapse;width:100%;font-size:14px}
.content th,.content td{padding:9px 12px;text-align:left;vertical-align:top;
  border-bottom:1px solid var(--border)}
.content th{background:var(--bg-alt);color:var(--heading);font-weight:650;white-space:nowrap}
.content tbody tr:last-child td{border-bottom:0}
.content blockquote{margin:1.2em 0;padding:.6em 1em;border-left:3px solid var(--accent);
  background:var(--bg-alt);border-radius:0 8px 8px 0;color:var(--fg-muted)}
.content hr{border:0;border-top:1px solid var(--border);margin:2.4em 0}
.headerlink{opacity:0;margin-left:.4em;font-weight:400;text-decoration:none}
h1:hover .headerlink,h2:hover .headerlink,h3:hover .headerlink,h4:hover .headerlink{opacity:.45}
.meta{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin:0 0 26px;
  font-size:12.5px;color:var(--fg-muted)}
.pill{padding:2px 9px;border:1px solid var(--border);border-radius:999px;background:var(--bg-alt)}
.pagenav{display:flex;gap:12px;justify-content:space-between;margin-top:56px;
  padding-top:20px;border-top:1px solid var(--border);font-size:14px}
.pagenav a{max-width:48%;padding:10px 14px;border:1px solid var(--border);border-radius:10px;background:var(--bg-alt)}
.pagenav a:hover{border-color:var(--accent);text-decoration:none}
.pagenav span{display:block;font-size:11px;text-transform:uppercase;letter-spacing:.06em;color:var(--fg-muted)}
.sitefoot{margin-top:40px;font-size:12.5px;color:var(--fg-muted)}
@media (max-width:900px){
  #navToggle{display:inline-grid}
  .layout{grid-template-columns:minmax(0,1fr)}
  .sidebar{display:none;position:fixed;top:56px;left:0;width:290px;z-index:25;
    border-right:1px solid var(--border);box-shadow:0 10px 40px rgba(0,0,0,.18)}
  body.nav-open .sidebar{display:block}
  .content{padding:24px 16px 64px}
  .content h1{font-size:1.6rem}
}