:root{
  --navy:#0b1e3a; --navy-600:#132c55; --navy-300:#2a4c86; --white:#ffffff;
  --gray-50:#f9fafb; --gray-100:#f3f4f6; --gray-300:#e5e7eb; --gray-500:#6b7280;
  --accent:#1f6feb;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0;font-family:system-ui,-apple-system,Segoe UI,Roboto,Helvetica,Arial,sans-serif;color:var(--navy);background:var(--gray-50)}
.container{max-width:1100px;margin:0 auto;padding:0 20px}
.header{background:linear-gradient(135deg,var(--navy),var(--navy-600));color:#fff}
.header .wrap{display:flex;align-items:center;gap:14px;padding:10px 0}

.site-title{margin:0;font-size:26px}
nav{background:#fff;border-bottom:1px solid var(--gray-300);position:sticky;top:0;z-index:50}
.nav-inner{display:flex;align-items:center;justify-content:space-between;gap:12px}
.menu{display:flex;flex-wrap:wrap;gap:10px}
.menu a{display:inline-block;color:var(--navy);text-decoration:none;padding:14px 10px;border-radius:8px;font-weight:600}
.menu a.active, .menu a:hover{background:#eef2ff}
.cta{background:var(--accent);color:#fff;padding:10px 14px;border-radius:8px;text-decoration:none;font-weight:700}
section{padding:48px 0}
h1,h2{margin:0 0 14px}
.lead{color:var(--gray-500);max-width:800px}
.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:18px;margin-top:18px}
.card{background:#fff;border:1px solid var(--gray-300);border-radius:12px;padding:18px}
.card h3{margin:0 0 6px;color:var(--navy-300)}
.list{columns:2;gap:32px}
@media (max-width:720px){.list{columns:1}}
footer{background:var(--navy);color:#cbd5e1;padding:28px 0;margin-top:40px}
footer a{color:#93c5fd;text-decoration:none}
/* Dark mode using system preference */
@media (prefers-color-scheme: dark){
  :root{--gray-50:#0b1020; --gray-100:#0e1529; --gray-300:#29324a; --gray-500:#9aa4b2;}
  html,body{background:var(--gray-100);color:#e6eefc}
  nav{background:#0f1830;border-bottom-color:#1d2740}
  .menu a{color:#dbe7ff}
  .card{background:#111c39;border-color:#1d2740}
  .lead{color:#a6b1c4}
}
/* Optional manual dark-mode toggle */
.theme-toggle{background:none;border:1px solid var(--gray-300);padding:8px 10px;border-radius:8px;color:inherit;cursor:pointer}

.header img {
  max-height: 100px;
  width: auto;
  height: auto;
  object-fit: contain;
  display: block;
}