/* ---------- Base & Theme ---------- */
:root{
  --bg: #f0f4ff;
  --card: #f9faff;
  --text: #222;
  --muted: #555;
  --accent: #3366ff;
  --accent-2: #8b33ff;
  --ring: rgba(51,102,255,0.35);
  --border: #ccd2e0;
  --shadow: 0 6px 16px rgba(0,0,0,0.12);
  --radius: 16px;
}
*{ box-sizing: border-box; margin:0; padding:0; }
body{
  font: 16px/1.6 system-ui, -apple-system, Segoe UI, Roboto, "Helvetica Neue", Arial, "Noto Sans", "Apple Color Emoji","Segoe UI Emoji";
  color:var(--text);
  background:
    radial-gradient(1200px 800px at 10% -10%, rgba(51,102,255,0.08), transparent 60%),
    radial-gradient(900px 600px at 110% 10%, rgba(139,51,255,0.08), transparent 60%),
    var(--bg);
}

a{ color:var(--accent); text-decoration: none; }
a:hover{ text-decoration: underline; }

/* ---------- Top Navigation ---------- */
nav.topnav {
  position: sticky; top: 0; z-index: 20;
  display: flex; justify-content: center; gap: 10px;
  backdrop-filter: blur(8px);
  background: color-mix(in oklab, var(--bg) 85%, white 15%);
  border-bottom: 1px solid var(--border);
  padding: 10px;
}
nav.topnav a {
  padding: 10px 16px;
  border-radius: 10px;
  color: var(--text);
  background: linear-gradient(to bottom, #ffffffcc, #f0f0ffcc);
  border: 1px solid var(--border);
  transition: transform .12s ease, background .12s ease, border-color .12s ease;
  font-weight: 500;
}
nav.topnav a:hover {
  transform: translateY(-1px);
  background: linear-gradient(to bottom, #ffffffee, #e8e8ffdd);
  border-color: var(--accent);
  text-decoration: none;
}
nav.topnav a.active {
  background: linear-gradient(to bottom, #dce4ff, #cdd9ff);
  border-color: var(--accent);
  font-weight: 700;
  color: var(--accent-2);
}

header{
  max-width: 960px;
  margin: 32px auto 12px;
  padding: 18px 22px;
  background: linear-gradient(135deg, rgba(51,102,255,0.15), rgba(139,51,255,0.12));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  text-align: center;
  font-weight: 700;
  font-size: clamp(22px, 3vw, 28px);
  color: var(--accent-2);
}

main{
  max-width: 960px;
  margin: 24px auto 40px;
  padding: 20px;
  background: linear-gradient(135deg, #ffffff, #f9f9ff);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

section{
  margin-bottom: 28px;
}
section h2{
  color: var(--accent-2);
  border-bottom: 2px solid var(--border);
  padding-bottom: 6px;
  margin-bottom: 14px;
  font-size: 20px;
}
section ul{ list-style: none; margin-left:0; }
section ul li{ margin-bottom: 8px; }

footer{
  max-width: 960px;
  margin: 24px auto 40px;
  padding: 14px 20px;
  color: var(--muted);
  border-top: 1px solid var(--border);
  text-align: center;
  border-radius: var(--radius);
  background: linear-gradient(135deg, rgba(51,102,255,0.1), rgba(139,51,255,0.08));
  box-shadow: var(--shadow);
}
footer a{ color: var(--accent-2); }

/* ---------- Typography ---------- */
h1,h2{ color: var(--accent-2); }
p{ color: var(--text); }
b{ color: var(--accent); }
i{ color: #444; }

hr{
  border: 0;
  border-top: 1px solid var(--border);
  margin: 24px 0;
}

/* ---------- Media ---------- */
img{
  display: block;
  width: 100%;
  max-width: 640px;
  height: auto;
  margin: 10px auto 18px;
  border-radius: calc(var(--radius) - 4px);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
}