:root {
  --bg: #0b1220; --bg2: #0f1830; --panel: #101b33; --panel2: #0c1528;
  --line: #22335a; --text: #e7ecf7; --text-dim: #8ea0c7; --text-faint: #5a6c92;
  --accent: #3ee0c8; --accent2: #ffb454; --accent3: #ff6b8b;
  --font-ui: 'Space Grotesk', 'Segoe UI', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', 'Courier New', monospace;
  --radius: 14px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-ui);
  line-height: 1.6;
}

.wrap { max-width: 860px; margin: 0 auto; padding: 0 18px 60px; }

/* ===== NAV ===== */
.site-nav {
  border-bottom: 1px solid var(--line);
  background: var(--panel);
  position: sticky; top: 0; z-index: 20;
}
.site-nav-inner {
  max-width: 860px; margin: 0 auto; padding: 12px 18px;
  display: flex; align-items: center; justify-content: space-between; gap: 12px;
}
.site-logo { display: flex; align-items: center; gap: 8px; text-decoration: none; color: var(--text); font-weight: 800; font-size: 17px; }
.site-logo svg { width: 28px; height: 28px; }
.site-nav-links { display: flex; gap: 16px; flex-wrap: wrap; font-size: 13.5px; }
.site-nav-links a { color: var(--text-dim); text-decoration: none; font-weight: 600; }
.site-nav-links a:hover, .site-nav-links a.active { color: var(--accent); }
.nav-toggle { display: none; background: none; border: 1px solid var(--line); color: var(--text); border-radius: 8px; padding: 6px 10px; cursor: pointer; }

@media (max-width: 640px) {
  .site-nav-links { display: none; flex-direction: column; width: 100%; padding-top: 10px; }
  .site-nav-links.open { display: flex; }
  .nav-toggle { display: block; }
  .site-nav-inner { flex-wrap: wrap; }
}

/* ===== CONTENT ===== */
h1 { font-size: 30px; font-weight: 800; letter-spacing: -0.5px; margin: 28px 0 8px; }
h2 { font-size: 21px; font-weight: 800; margin: 32px 0 10px; color: var(--text); }
h3 { font-size: 16.5px; font-weight: 700; margin: 22px 0 8px; color: var(--accent); }
p { color: var(--text-dim); margin: 0 0 14px; }
.lede { font-size: 16px; color: var(--text-dim); }
a { color: var(--accent); }
ul, ol { color: var(--text-dim); padding-left: 22px; }
li { margin-bottom: 6px; }

.card {
  background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 16px 18px; margin: 16px 0;
}
.card-label { font-size: 10.5px; text-transform: uppercase; letter-spacing: 1.4px; color: var(--text-faint); font-weight: 700; margin-bottom: 8px; }

.grid-links {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(160px, 1fr)); gap: 10px; margin: 18px 0;
}
.grid-links a {
  display: block; background: var(--panel); border: 1px solid var(--line); border-radius: 12px;
  padding: 14px; text-decoration: none; color: var(--text); font-weight: 700; font-size: 14px;
  transition: border-color .15s;
}
.grid-links a:hover { border-color: var(--accent); }
.grid-links a span { display: block; font-weight: 400; color: var(--text-faint); font-size: 12px; margin-top: 4px; }

.formula-box {
  font-family: var(--font-mono); background: var(--bg2); border: 1px solid var(--line);
  border-radius: 10px; padding: 12px 16px; margin: 14px 0; color: var(--accent); font-size: 15px;
  overflow-x: auto;
}

.cta-sim {
  display: block; text-align: center; background: linear-gradient(90deg, var(--accent), #2bb3a3);
  color: #04211d; font-weight: 800; padding: 14px; border-radius: 12px; text-decoration: none;
  margin: 22px 0; font-size: 15px;
}

.breadcrumb { font-size: 12.5px; color: var(--text-faint); margin: 18px 0 4px; }
.breadcrumb a { color: var(--text-faint); }

table { width: 100%; border-collapse: collapse; margin: 14px 0; font-size: 14px; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--line); color: var(--text-dim); }
th { color: var(--text); font-size: 12px; text-transform: uppercase; letter-spacing: .5px; }

.site-footer {
  border-top: 1px solid var(--line); margin-top: 50px; padding: 24px 18px;
  color: var(--text-faint); font-size: 12.5px; text-align: center;
}
.site-footer a { color: var(--text-faint); }

.katex-display { color: var(--text); margin: 18px 0; overflow-x: auto; }
.katex { color: var(--text); }