:root {
  --bg: #07111f;
  --panel: #0d1b2e;
  --ink: #e8eef7;
  --muted: #9bb0c9;
  --line: rgba(255, 255, 255, 0.08);
  --accent: #3dd6c6;
  --accent-2: #7aa2ff;
  --warn: #ffd28a;
  --warn-bg: rgba(255, 210, 138, 0.08);
  --radius: 18px;
  --shadow: 0 20px 60px rgba(0, 0, 0, 0.35);
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(1200px 600px at 10% -10%, rgba(61, 214, 198, 0.16), transparent 60%),
    radial-gradient(900px 500px at 90% 0%, rgba(122, 162, 255, 0.18), transparent 55%),
    var(--bg);
  line-height: 1.6;
}
a { color: var(--accent-2); text-decoration: none; }
a:hover { text-decoration: underline; }
.wrap { width: min(1100px, calc(100% - 2rem)); margin: 0 auto; }
.skip {
  position: absolute; left: -999px; top: 0;
}
.skip:focus { left: 1rem; top: 1rem; background: #000; padding: 0.5rem 1rem; z-index: 20; }

.top {
  position: sticky; top: 0; z-index: 10;
  backdrop-filter: blur(14px);
  background: rgba(7, 17, 31, 0.75);
  border-bottom: 1px solid var(--line);
}
.bar { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: 0.9rem 0; }
.brand { color: var(--ink); font-weight: 700; letter-spacing: 0.02em; font-size: 1.05rem; }
.brand span { color: var(--accent); }
nav { display: flex; flex-wrap: wrap; gap: 0.9rem; }
nav a { color: var(--muted); font-size: 0.95rem; }

.hero { padding: 4.5rem 0 2rem; }
.eyebrow { color: var(--accent); text-transform: uppercase; letter-spacing: 0.12em; font-size: 0.75rem; margin: 0 0 1rem; }
h1 { font-size: clamp(2rem, 5vw, 3.4rem); line-height: 1.1; margin: 0 0 1rem; max-width: 16ch; }
.lede { font-size: 1.15rem; color: var(--muted); max-width: 52rem; }
.cta { display: flex; flex-wrap: wrap; gap: 0.75rem; margin: 1.75rem 0; }
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  border-radius: 999px; padding: 0.75rem 1.2rem; font-weight: 600;
  border: 1px solid transparent; transition: transform 0.15s ease, background 0.15s ease;
}
.btn:hover { transform: translateY(-1px); text-decoration: none; }
.btn.primary { background: linear-gradient(135deg, var(--accent), #2bb3d8); color: #042018; }
.btn.ghost { border-color: var(--line); color: var(--ink); background: rgba(255,255,255,0.03); }
.btn.quiet { color: var(--muted); border-color: transparent; }

.warn {
  margin-top: 1.5rem; padding: 1rem 1.15rem; border-radius: var(--radius);
  border: 1px solid rgba(255, 210, 138, 0.25); background: var(--warn-bg); color: var(--warn);
}

.grid-3 {
  display: grid; gap: 1rem; padding: 1rem 0 3rem;
  grid-template-columns: repeat(3, minmax(0, 1fr));
}
.card {
  background: rgba(13, 27, 46, 0.85); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 1.25rem; box-shadow: var(--shadow);
}
.card h2 { margin: 0 0 0.5rem; font-size: 1.15rem; }
.card p { margin: 0; color: var(--muted); }

.band { padding: 3rem 0; border-block: 1px solid var(--line); background: rgba(0,0,0,0.18); }
.section-lede { color: var(--muted); max-width: 48rem; }
.diagram, .code {
  overflow: auto; padding: 1.1rem 1.25rem; border-radius: var(--radius);
  background: #050b14; border: 1px solid var(--line); color: #cfe0f5;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 0.9rem;
}
.list { color: var(--muted); padding-left: 1.2rem; }
.list li { margin: 0.45rem 0; }
.note { color: var(--muted); font-size: 0.95rem; }
.foot { border-top: 1px solid var(--line); margin-top: 3rem; color: var(--muted); font-size: 0.9rem; }

@media (max-width: 860px) {
  .grid-3 { grid-template-columns: 1fr; }
  nav { display: none; }
  h1 { max-width: none; }
}