:root {
  --bg: #0b1220;
  --surface: #121b2e;
  --surface-2: #18233a;
  --border: #24314d;
  --text: #e6ebf5;
  --muted: #9aa8c2;
  --accent: #2dd4bf;
  --accent-2: #60a5fa;
  --danger: #f87171;
  --radius: 12px;
  --max: 1120px;
  font-family: "Inter", "Segoe UI", system-ui, -apple-system, Roboto, sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--bg); color: var(--text); line-height: 1.6; }
img { max-width: 100%; height: auto; display: block; }
a { color: var(--accent); }
a:focus-visible, button:focus-visible, input:focus-visible, select:focus-visible, textarea:focus-visible {
  outline: 2px solid var(--accent-2); outline-offset: 2px;
}

.container { width: min(var(--max), 100% - 32px); margin-inline: auto; }

/* ---------- header / nav ---------- */
.site-header {
  position: sticky; top: 0; z-index: 10;
  background: rgba(11, 18, 32, 0.92); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--text); text-decoration: none; font-weight: 700; }
.brand img { width: 32px; height: 32px; }
.nav-toggle {
  display: none; background: none; border: 1px solid var(--border); color: var(--text);
  border-radius: 8px; padding: 6px 10px; font-size: 1rem; cursor: pointer;
}
.site-nav ul { list-style: none; display: flex; gap: 4px; margin: 0; padding: 0; }
.site-nav a {
  display: block; padding: 8px 12px; border-radius: 8px; color: var(--muted);
  text-decoration: none; font-size: 0.95rem;
}
.site-nav a:hover { color: var(--text); background: var(--surface); }
.site-nav a[aria-current="page"] { color: var(--bg); background: var(--accent); font-weight: 600; }

@media (max-width: 820px) {
  .nav-toggle { display: block; }
  .site-nav { display: none; position: absolute; top: 64px; left: 0; right: 0;
    background: var(--bg); border-bottom: 1px solid var(--border); }
  .site-nav.open { display: block; }
  .site-nav ul { flex-direction: column; padding: 8px 16px 16px; }
}

/* ---------- layout ---------- */
main { padding-block: 48px 72px; }
.hero { display: grid; grid-template-columns: 1.1fr 1fr; gap: 40px; align-items: center; }
.hero h1 { font-size: clamp(2rem, 4vw, 3rem); line-height: 1.15; margin: 0 0 16px; }
.eyebrow { color: var(--accent); font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; font-size: 0.8rem; }
.lead { color: var(--muted); font-size: 1.1rem; }
.page-head { margin-bottom: 32px; max-width: 760px; }
.page-head h1 { font-size: clamp(1.8rem, 3.2vw, 2.4rem); margin: 0 0 8px; }
h2 { margin-top: 48px; }
.grid { display: grid; gap: 20px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
@media (max-width: 820px) {
  .hero, .grid-3, .grid-2 { grid-template-columns: 1fr; }
}

.card {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 22px;
}
.card h3 { margin-top: 0; }
.card p { color: var(--muted); }
.tag {
  display: inline-block; font-size: 0.75rem; padding: 2px 10px; border-radius: 999px;
  background: var(--surface-2); color: var(--accent-2); border: 1px solid var(--border);
}

.btn {
  display: inline-block; padding: 10px 18px; border-radius: 10px; border: 1px solid var(--accent);
  background: var(--accent); color: var(--bg); font-weight: 600; text-decoration: none; cursor: pointer; font-size: 1rem;
}
.btn.secondary { background: transparent; color: var(--accent); }
.btn-row { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 24px; }

/* ---------- strategies filter ---------- */
.filters { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 20px; }
.filters button {
  background: var(--surface); color: var(--muted); border: 1px solid var(--border);
  padding: 6px 14px; border-radius: 999px; cursor: pointer;
}
.filters button[aria-pressed="true"] { background: var(--accent-2); color: var(--bg); border-color: var(--accent-2); }
.strategy[hidden] { display: none; }
.metrics { display: flex; gap: 16px; font-size: 0.9rem; color: var(--muted); }
.metrics strong { color: var(--text); }

/* ---------- backtest ---------- */
.sim { display: grid; grid-template-columns: 320px 1fr; gap: 24px; }
@media (max-width: 820px) { .sim { grid-template-columns: 1fr; } }
.form-row { display: grid; gap: 6px; margin-bottom: 14px; }
label { font-size: 0.9rem; color: var(--muted); }
input, select, textarea {
  width: 100%; padding: 10px 12px; border-radius: 8px; border: 1px solid var(--border);
  background: var(--surface-2); color: var(--text); font: inherit;
}
.chart-wrap { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px; }
.chart-wrap svg { width: 100%; height: 280px; display: block; }
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; margin-top: 16px; }
@media (max-width: 560px) { .stats { grid-template-columns: repeat(2, 1fr); } }
.stat { background: var(--surface-2); border-radius: 10px; padding: 12px; }
.stat span { display: block; font-size: 0.8rem; color: var(--muted); }
.stat strong { font-size: 1.15rem; }
.note { font-size: 0.85rem; color: var(--muted); }

/* ---------- contact ---------- */
.field-error { color: var(--danger); font-size: 0.85rem; min-height: 1.2em; }
input[aria-invalid="true"], textarea[aria-invalid="true"] { border-color: var(--danger); }
.form-status { margin-top: 12px; padding: 12px; border-radius: 10px; background: var(--surface-2); }
.form-status[hidden] { display: none; }

/* ---------- 404 ---------- */
.error-wrap { text-align: center; padding-block: 48px; }
.error-code { font-size: clamp(4rem, 12vw, 7rem); font-weight: 800; color: var(--accent); margin: 0; line-height: 1; }

/* ---------- footer ---------- */
.site-footer { border-top: 1px solid var(--border); padding-block: 24px; color: var(--muted); font-size: 0.9rem; }
.footer-inner { display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; }
table { width: 100%; border-collapse: collapse; }
th, td { text-align: left; padding: 10px; border-bottom: 1px solid var(--border); }
th { color: var(--muted); font-weight: 600; font-size: 0.9rem; }