:root{
  --bg:#f4f7ff;--card:#fff;--text:#0f172a;--muted:#475569;--border:#e2e8f0;
  --primary:#2563eb;--primary-600:#1d4ed8;--accent:#60a5fa;
  --radius:16px;--shadow:0 12px 28px rgba(15,23,42,.10);
}
@media (prefers-color-scheme: dark){
  :root{--bg:#0b1220;--card:#0f172a;--text:#e5e7eb;--muted:#94a3b8;--border:#1f2937;--shadow:0 12px 28px rgba(0,0,0,.35);}
}
*{box-sizing:border-box}
html,body{height:100%}
body{margin:0;font-family:Inter,system-ui,Segoe UI,Roboto,Arial,sans-serif;background:
  radial-gradient(1100px 700px at 20% -10%, #e0f2fe 0%, transparent 55%),
  radial-gradient(900px 600px at 100% 0%, #dbeafe 0%, transparent 60%),var(--bg);color:var(--text);}
a{color:var(--primary-600)}
.wrap{max-width:1100px;margin:0 auto;padding:0 20px}

/* Header */
.site-header{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.55);backdrop-filter:saturate(140%) blur(10px);border-bottom:1px solid var(--border)}
@media (prefers-color-scheme: dark){.site-header{background:rgba(15,23,42,.55)}}
.header-inner{display:flex;align-items:center;justify-content:space-between;padding:12px 0}
.brand{display:flex;align-items:center;gap:12px;color:inherit;text-decoration:none}
.logo{width:36px;height:36px;border-radius:10px;background:linear-gradient(135deg,var(--primary),var(--accent));box-shadow:0 8px 18px rgba(37,99,235,.25)}
.brand-text{font-weight:800;letter-spacing:.3px}
.site-nav{display:flex;gap:16px;align-items:center}
.site-nav a{color:inherit;text-decoration:none;padding:8px 10px;border-radius:10px}
.site-nav a:hover{background:rgba(99,102,241,.08)}
.btn{border:1px solid var(--border);background:var(--card);border-radius:999px;padding:8px 14px;cursor:pointer}
.btn.primary{background:var(--primary);border-color:var(--primary);color:#fff}
.btn.ghost{background:transparent}

/* Hero */
.hero{padding:64px 0}
.hero h1{font-size:40px;margin:0 0 8px}
.lead{color:var(--muted);max-width:75ch}
.accent{background:linear-gradient(90deg,var(--primary),#7c3aed);-webkit-background-clip:text;background-clip:text;color:transparent}
.cta-row{display:flex;gap:12px;margin-top:16px;flex-wrap:wrap}

/* Sections */
section.card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:22px;margin:24px 0}
h2{margin:0 0 10px;font-size:24px}
h3{margin:14px 0 8px}
.muted{color:var(--muted)}
.grid.two{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:16px}
.note{border:1px solid var(--border);border-radius:12px;padding:12px}
.code{font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;background:#eef2ff;border:1px solid #e0e7ff;border-radius:8px;padding:2px 6px}
table{width:100%;border-collapse:collapse}
th,td{border:1px solid var(--border);padding:8px;text-align:left}
th{background:#f8fafc}
@media (prefers-color-scheme: dark){th{background:#0b1220}}

/* Simulator */
.simulator{display:grid;gap:12px}
canvas{display:block;width:100%;background:linear-gradient(180deg,#fafafa,#f5f7fb);border:1px solid var(--border);border-radius:12px}
#simCanvas{height:160px;}
#plotCanvas{height:120px;}
@media (prefers-color-scheme: dark){canvas{background:linear-gradient(180deg,#0e1425,#0b1220)}}
.controls{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:10px;align-items:center}
.controls label{display:flex;align-items:center;gap:8px}
.controls input[type=range]{width:100%}
.tiny{font-size:12px}

/* Gallery */
.gallery{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:10px}
.gallery figure{margin:0}
.gallery img{width:100%;height:140px;object-fit:cover;border-radius:12px;border:1px solid var(--border);cursor:pointer}
.uploader{display:flex;gap:10px;align-items:center;flex-wrap:wrap}

/* Lightbox */
.lightbox{position:fixed;inset:0;background:rgba(0,0,0,.85);display:none;align-items:center;justify-content:center;z-index:60}
.lightbox img{max-width:92vw;max-height:90vh;border-radius:16px}

/* Footer */
footer{padding:24px 0;color:var(--muted)}