:root {
  --bg: #0b1020;
  --bg-soft: #101830;
  --card: #121a30;
  --border: #1e2a4a;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --accent: #38bdf8;
  --accent-2: #a78bfa;
  --success: #34d399;
  --danger: #f87171;
  --radius: 14px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.6;
}

h1, h2, h3 { line-height: 1.2; margin: 0 0 0.5em; }
p { margin: 0 0 1em; }
a { color: var(--accent); }

/* ---------- Nav ---------- */
.nav { position: sticky; top: 0; z-index: 10; background: rgba(11, 16, 32, 0.85); backdrop-filter: blur(8px); border-bottom: 1px solid var(--border); }
.nav-inner { max-width: 1080px; margin: 0 auto; padding: 0.9rem 1.25rem; display: flex; justify-content: space-between; align-items: center; }
.nav-brand { font-weight: 800; font-size: 1.25rem; letter-spacing: -0.02em; }
.nav-links { display: flex; gap: 1.25rem; }
.nav-links a { color: var(--muted); text-decoration: none; font-size: 0.95rem; }
.nav-links a:hover { color: var(--accent); }

/* ---------- Hero ---------- */
.hero { padding: 6rem 1.25rem 4rem; text-align: center; background: radial-gradient(900px 400px at 50% -10%, rgba(56, 189, 248, 0.12), transparent); }
.hero-inner { max-width: 760px; margin: 0 auto; }
.eyebrow { text-transform: uppercase; letter-spacing: 0.18em; font-size: 0.78rem; color: var(--accent); font-weight: 700; }
.hero h1 { font-size: clamp(2.4rem, 6vw, 3.8rem); letter-spacing: -0.03em; margin-bottom: 0.2em; }
.gradient-text { background: linear-gradient(90deg, var(--accent), var(--accent-2)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.lede { font-size: 1.15rem; color: var(--muted); max-width: 620px; margin: 0 auto 2rem; }
.hero-actions { display: flex; gap: 0.75rem; justify-content: center; flex-wrap: wrap; }

/* ---------- Buttons ---------- */
.btn { display: inline-block; padding: 0.7rem 1.4rem; border-radius: 999px; font-weight: 600; font-size: 0.98rem; text-decoration: none; border: 1px solid transparent; cursor: pointer; transition: transform 0.15s ease, box-shadow 0.15s ease; }
.btn:hover { transform: translateY(-1px); }
.btn-primary { background: linear-gradient(90deg, #0ea5e9, #6366f1); color: #fff; box-shadow: 0 8px 24px rgba(14, 165, 233, 0.35); }
.btn-ghost { background: transparent; color: var(--text); border-color: var(--border); }
.btn-ghost:hover { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(56, 189, 248, 0.15); }

/* ---------- Sections ---------- */
.section { max-width: 1080px; margin: 0 auto; padding: 4.5rem 1.25rem; }
.section h2 { font-size: clamp(1.8rem, 4vw, 2.5rem); letter-spacing: -0.02em; }
.section-lede { color: var(--muted); font-size: 1.08rem; max-width: 680px; }

.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 1.25rem; margin-top: 2rem; }
.card { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 1.5rem; }
.card h3 { color: var(--accent); font-size: 1.2rem; }
.card p { color: var(--muted); margin: 0; }

/* ---------- Diagram ---------- */
.diagram-card { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 1.5rem; display: flex; flex-direction: column; align-items: center; gap: 1.5rem; }
.diagram { width: min(520px, 100%); height: auto; }
.flow-arrow { opacity: 0.55; filter: drop-shadow(0 0 5px rgba(56, 189, 248, 0.55)); }
.flow-arrow.loop { animation: dash 1.2s linear infinite; }
@keyframes dash { to { stroke-dashoffset: -40; } }
.flow-dot { filter: drop-shadow(0 0 6px rgba(125, 211, 252, 0.95)); }
.node { cursor: pointer; }
.node circle { fill: #0b1020; stroke: var(--accent); stroke-width: 2.5; transition: stroke 0.2s ease, filter 0.2s ease; animation: node-pulse 2.6s ease-in-out infinite; transform-box: fill-box; transform-origin: center; filter: drop-shadow(0 0 6px rgba(56, 189, 248, 0.35)); }
.node text { fill: var(--text); font-size: 30px; pointer-events: none; }
@keyframes node-pulse { 0%, 100% { transform: scale(1); opacity: 1; } 50% { transform: scale(1.07); opacity: 0.85; } }
.node:hover circle { filter: drop-shadow(0 0 10px rgba(56, 189, 248, 0.7)); animation-play-state: paused; }
.node.active circle { stroke: var(--accent-2); stroke-width: 3.5; filter: drop-shadow(0 0 14px rgba(167, 139, 250, 0.9)); animation: none; }

.stage-detail { background: var(--bg-soft); border: 1px solid var(--border); border-radius: var(--radius); padding: 1.25rem 1.5rem; width: min(520px, 100%); }
.stage-detail h3 { color: var(--accent-2); margin-bottom: 0.25em; }
.stage-detail p { color: var(--muted); margin: 0; }
.stage-meta { font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.12em; color: var(--muted) !important; margin-top: 0.75rem !important; }

/* ---------- Simulator ---------- */
.simulator { margin-top: 2.5rem; background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 1.75rem; }
.simulator h3 { font-size: 1.4rem; }
.sim-sub { color: var(--muted); margin-bottom: 1.25rem; }

.sim-controls { display: flex; justify-content: space-between; align-items: center; gap: 1rem; flex-wrap: wrap; margin-bottom: 1.25rem; }
.chips { display: flex; gap: 0.5rem; flex-wrap: wrap; }
.chip { padding: 0.45rem 1rem; border-radius: 999px; border: 1px solid var(--border); background: var(--bg-soft); color: var(--muted); font-weight: 600; font-size: 0.88rem; cursor: pointer; transition: all 0.15s ease; }
.chip:hover { border-color: var(--accent); color: var(--text); }
.chip.active { background: linear-gradient(90deg, rgba(14, 165, 233, 0.25), rgba(99, 102, 241, 0.25)); border-color: var(--accent); color: var(--text); }

.sim-buttons { display: flex; gap: 0.6rem; flex-wrap: wrap; }

.log { background: #080c18; border: 1px solid var(--border); border-radius: var(--radius); padding: 1rem 1.25rem; min-height: 150px; max-height: 220px; overflow-y: auto; font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 0.85rem; }
.log-entry { padding: 0.2rem 0; border-bottom: 1px solid rgba(30, 42, 74, 0.5); }
.log-entry:last-child { border-bottom: none; }
.log-entry.stage { color: var(--accent); font-weight: 700; }
.log-entry.good { color: var(--success); }
.log-entry.bad { color: var(--danger); }
.log-entry.dim { color: var(--muted); }

.metrics { margin-top: 1.5rem; display: flex; flex-direction: column; gap: 1rem; }
.metric-label { display: flex; justify-content: space-between; font-size: 0.9rem; color: var(--muted); margin-bottom: 0.35rem; }
.metric-label span:last-child { color: var(--text); font-weight: 700; }
.bar { height: 10px; background: var(--bg-soft); border-radius: 999px; overflow: hidden; border: 1px solid var(--border); }
.bar-fill { height: 100%; width: 0%; border-radius: 999px; background: linear-gradient(90deg, #0ea5e9, #a78bfa); transition: width 0.7s ease; }

/* ---------- Footer ---------- */
.footer { border-top: 1px solid var(--border); padding: 2.5rem 1.25rem; text-align: center; color: var(--muted); font-size: 0.9rem; }

/* ---------- Responsive ---------- */
@media (max-width: 700px) {
  .nav-links { display: none; }
  .sim-controls { flex-direction: column; align-items: flex-start; }
}