:root{
  --bg:#f6f8f7;
  --panel:#fff;
  --ink:#1d2925;
  --muted:#66736d;
  --line:#e1e8e4;
  --brand:#017680;
  --brand-dark:#07535a;
  --brand-soft:#e8f5f5;
  --accent:#d99a2b;
  --shadow:0 10px 30px rgba(20,50,45,.07);
  --radius:12px;
  --maxw:1280px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink);font-family:"Hind Siliguri","Noto Sans Bengali","Segoe UI",Arial,sans-serif;line-height:1.75}
body.menu-open{overflow:hidden}
h1,h2,h3,.brand-title{font-family:"Noto Serif Bengali","Georgia",serif}
a{color:var(--brand-dark)}
a:focus-visible,button:focus-visible,input:focus-visible{outline:3px solid rgba(1,118,128,.28);outline-offset:2px}
.skip-link{position:absolute;left:-999px;top:0;background:var(--brand);color:#fff;padding:8px 14px;border-radius:0 0 8px 0;z-index:1000}.skip-link:focus{left:0}
.site-header{background:linear-gradient(135deg,#07535a,#017680);color:#fff;box-shadow:0 2px 12px rgba(0,0,0,.08);position:relative;z-index:20}
.site-header .wrap{max-width:var(--maxw);margin:0 auto;padding:18px 28px;display:flex;align-items:center;justify-content:space-between;gap:20px}
.brand-title{font-size:1.35rem;margin:0;color:#fff;font-weight:700}.brand-sub{font-size:.88rem;color:#d9f0f1;margin:1px 0 0}.header-note{display:none}
.layout{max-width:var(--maxw);margin:0 auto;display:grid;grid-template-columns:300px minmax(0,1fr);align-items:start}
.sidebar{min-width:0}.sidebar-inner{position:sticky;top:0}
#tutorial-menu{position:sticky;top:0;max-height:100vh;overflow:auto;padding:18px 14px 28px;border-right:1px solid var(--line);background:rgba(246,248,247,.96);scrollbar-width:thin}
.sidebar-head{display:flex;align-items:center;gap:8px;margin-bottom:12px}.home-link{display:flex;align-items:center;gap:9px;flex:1;padding:10px 12px;border-radius:10px;text-decoration:none;color:var(--brand-dark);font-weight:700;background:var(--brand-soft)}.home-icon{font-size:1.15rem;line-height:1}.menu-close{display:none;border:0;background:transparent;font-size:1.8rem;line-height:1;color:var(--muted);cursor:pointer;padding:4px 8px}
.menu-search{display:flex;align-items:center;position:relative;background:#fff;border:1px solid var(--line);border-radius:10px;margin:0 2px 14px}.menu-search:focus-within{border-color:var(--brand);box-shadow:0 0 0 3px rgba(1,118,128,.08)}.menu-search input{width:100%;border:0;background:transparent;padding:9px 34px 9px 34px;font:inherit;font-size:.9rem;outline:0;color:var(--ink)}.search-icon{position:absolute;left:11px;color:var(--muted);font-size:1.05rem}.menu-search button{position:absolute;right:6px;border:0;background:transparent;color:var(--muted);cursor:pointer;font-size:1.1rem}.menu-results{font-size:.76rem;color:var(--muted);padding:0 8px 7px;min-height:0}
.menu-section{margin:0 0 17px}.menu-section h2{font-family:inherit;font-size:.72rem;line-height:1.4;color:#71807a;margin:0 8px 5px;font-weight:700;text-transform:none}.menu-section ul{list-style:none;margin:0;padding:0}.menu-section li{margin:1px 0}.menu-section a{display:block;padding:6px 10px;border-radius:8px;color:#30403b;text-decoration:none;font-size:.88rem;line-height:1.45}.menu-section a:hover{background:#e9efec;color:var(--brand-dark)}.menu-section a.active{background:var(--brand);color:#fff;font-weight:600;box-shadow:0 3px 9px rgba(1,118,128,.18)}
main{padding:38px 48px 80px;min-width:0}.breadcrumb{font-size:.83rem;color:var(--muted);margin:0 0 20px}.breadcrumb a{color:var(--muted);text-decoration:none}.breadcrumb a:hover{text-decoration:underline;color:var(--brand-dark)}
article{max-width:850px;background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);padding:34px 38px;box-shadow:var(--shadow)}article h1{font-size:2rem;line-height:1.35;margin:0 0 22px;color:var(--brand-dark)}article p{margin:0 0 16px}article ul,article ol{margin:0 0 20px;padding-inline-start:1.45em}article li{margin-bottom:8px}article img{display:block;max-width:100%;height:auto;border:1px solid var(--line);border-radius:10px;margin:18px auto 24px;background:#fff;box-shadow:0 5px 18px rgba(20,50,45,.06)}
.note{background:#fff6e6;border-inline-start:4px solid var(--accent);padding:12px 16px;border-radius:7px;margin:0 0 20px}.video-note{background:var(--brand-soft);border-inline-start:4px solid var(--brand);padding:12px 16px;border-radius:7px;margin:0 0 20px;font-size:.95rem}
.pager{display:flex;justify-content:space-between;gap:16px;margin:30px 0 0;padding-top:20px;border-top:1px solid var(--line);flex-wrap:wrap}.pager a{flex:1 1 220px;border:1px solid var(--line);border-radius:10px;padding:12px 16px;text-decoration:none;color:var(--ink);background:#fff;transition:.15s ease}.pager a:hover{border-color:#a9cfce;transform:translateY(-1px);box-shadow:var(--shadow)}.pager .dir{display:block;font-size:.72rem;color:var(--muted);margin-bottom:3px}.pager .next{text-align:end}
.index-hero{background:linear-gradient(135deg,#07535a,#017680);color:#f4ffff;border-radius:16px;padding:42px 40px;margin-bottom:28px;box-shadow:var(--shadow)}.index-hero h1{color:#fff;margin:0 0 10px;font-size:2.05rem;line-height:1.4}.index-hero p{margin:0;color:#d9f0f1;max-width:68ch}.cat-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(250px,1fr));gap:16px}.cat-card{border:1px solid var(--line);border-radius:var(--radius);padding:20px 22px;background:#fff;box-shadow:0 4px 16px rgba(20,50,45,.045);transition:.15s ease}.cat-card:hover{transform:translateY(-2px);box-shadow:var(--shadow)}.cat-card h2{font-size:1.03rem;line-height:1.45;margin:0 0 11px;color:var(--brand-dark)}.cat-card ul{list-style:none;margin:0;padding:0}.cat-card li{margin-bottom:7px}.cat-card a{text-decoration:none;font-size:.92rem}.cat-card a:hover{text-decoration:underline}
.site-footer{border-top:1px solid var(--line);padding:26px 24px 50px;text-align:center;color:var(--muted);font-size:.82rem;background:#fff}.site-footer p{margin:0}
.mobile-menu-button{display:none}
@media (max-width:900px){
  .site-header .wrap{padding:16px 20px}.layout{display:block}.mobile-menu-button{display:inline-flex;align-items:center;gap:7px;margin:16px 20px 0;border:1px solid var(--line);background:#fff;color:var(--brand-dark);border-radius:9px;padding:9px 13px;font:inherit;font-weight:600;cursor:pointer;box-shadow:0 3px 12px rgba(20,50,45,.05)}
  #tutorial-menu{position:fixed;z-index:100;top:0;left:0;bottom:0;width:min(88vw,350px);max-height:none;padding:16px 14px 30px;border-right:1px solid var(--line);background:#f8faf9;transform:translateX(-105%);transition:transform .22s ease;box-shadow:8px 0 30px rgba(0,0,0,.12)}
  body.menu-open #tutorial-menu{transform:translateX(0)}
  body.menu-open:after{content:"";position:fixed;inset:0;background:rgba(8,31,29,.42);z-index:90}
  .menu-close{display:block}.sidebar{height:0}.sidebar:before{content:""}main{padding:26px 20px 60px}.index-hero{padding:30px 24px}.index-hero h1{font-size:1.75rem}article{padding:28px 24px}
}
@media (max-width:600px){.brand-title{font-size:1.15rem}.brand-sub{font-size:.8rem}.site-header .wrap{padding:14px 16px}.mobile-menu-button{margin:12px 16px 0}main{padding:22px 16px 50px}.index-hero{padding:26px 20px;border-radius:13px}.index-hero h1{font-size:1.5rem}.cat-grid{grid-template-columns:1fr}.cat-card{padding:18px}.breadcrumb{font-size:.78rem}article{padding:22px 18px;border-radius:10px}article h1{font-size:1.6rem}.pager{gap:10px}.pager a{flex-basis:100%}.pager .next{text-align:start}}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}#tutorial-menu,.cat-card,.pager a{transition:none}}