:root {
  color-scheme: light;
  --ink: #111827;
  --muted: #526070;
  --line: #dbe3ec;
  --paper: #f7f9fc;
  --white: #ffffff;
  --blue: #2563eb;
  --blue-dark: #1746a2;
  --cyan: #06b6d4;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.65;
}

a { color: var(--blue-dark); }

.shell { width: min(1120px, calc(100% - 40px)); margin: 0 auto; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid rgba(219, 227, 236, .9);
  background: rgba(247, 249, 252, .92);
  backdrop-filter: blur(18px);
}

.nav {
  min-height: 70px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 760;
  text-decoration: none;
  letter-spacing: -.02em;
}

.brand-mark {
  width: 34px;
  height: 34px;
  border-radius: 10px;
  display: grid;
  place-items: center;
  color: white;
  background: linear-gradient(145deg, var(--blue), var(--cyan));
  box-shadow: 0 8px 20px rgba(37, 99, 235, .24);
  font: 700 18px/1 ui-monospace, SFMono-Regular, Menlo, monospace;
}

.nav-links { display: flex; align-items: center; gap: 24px; }
.nav-links a { color: #334155; text-decoration: none; font-weight: 620; }
.nav-links a:hover, .nav-links a:focus-visible { color: var(--blue); }

.hero {
  position: relative;
  overflow: hidden;
  padding: 100px 0 78px;
  background:
    linear-gradient(rgba(37,99,235,.055) 1px, transparent 1px),
    linear-gradient(90deg, rgba(37,99,235,.055) 1px, transparent 1px),
    radial-gradient(circle at 75% 18%, rgba(6,182,212,.17), transparent 30%),
    var(--white);
  background-size: 36px 36px, 36px 36px, auto, auto;
}

.hero-grid { display: grid; grid-template-columns: 1.15fr .85fr; gap: 58px; align-items: center; }
.eyebrow { margin: 0 0 15px; color: var(--blue); font-weight: 760; letter-spacing: .11em; text-transform: uppercase; font-size: .8rem; }
h1, h2, h3 { line-height: 1.12; letter-spacing: -.035em; }
h1 { margin: 0; max-width: 760px; font-size: clamp(2.8rem, 6vw, 5.4rem); }
.lede { max-width: 680px; margin: 24px 0 0; color: var(--muted); font-size: clamp(1.08rem, 2vw, 1.3rem); }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 34px; }
.button { display: inline-flex; align-items: center; justify-content: center; min-height: 48px; padding: 0 20px; border-radius: 13px; font-weight: 720; text-decoration: none; }
.button-primary { color: white; background: var(--blue); box-shadow: 0 10px 24px rgba(37,99,235,.24); }
.button-secondary { color: var(--ink); background: white; border: 1px solid var(--line); }

.graph-card {
  min-height: 370px;
  border: 1px solid #cbd7e6;
  border-radius: 28px;
  padding: 24px;
  color: white;
  background: linear-gradient(150deg, #0f172a 0%, #172554 62%, #164e63 100%);
  box-shadow: 0 28px 70px rgba(15, 23, 42, .24);
}
.graph-top { display: flex; justify-content: space-between; color: #bfdbfe; font: 600 .84rem/1.2 ui-monospace, SFMono-Regular, Menlo, monospace; }
.equation { margin: 38px 0 22px; font: 700 clamp(1.5rem, 3vw, 2.2rem)/1.2 ui-monospace, SFMono-Regular, Menlo, monospace; }
.plot { position: relative; height: 190px; border-left: 1px solid rgba(255,255,255,.32); border-bottom: 1px solid rgba(255,255,255,.32); overflow: hidden; }
.plot::before { content: ""; position: absolute; inset: 12% 4% 8%; border-top: 4px solid #67e8f9; border-radius: 50%; transform: rotate(-8deg) skewX(-10deg); box-shadow: 0 -15px 25px rgba(103,232,249,.3); }
.plot::after { content: ""; position: absolute; left: 50%; top: 0; bottom: 0; border-left: 1px dashed rgba(255,255,255,.23); }

.section { padding: 78px 0; }
.section-white { background: var(--white); }
.section-head { max-width: 720px; margin-bottom: 34px; }
.section h2 { margin: 0 0 12px; font-size: clamp(2rem, 4vw, 3.15rem); }
.section-head p { color: var(--muted); margin: 0; font-size: 1.08rem; }
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.card { padding: 26px; border: 1px solid var(--line); border-radius: 20px; background: white; box-shadow: 0 12px 34px rgba(15,23,42,.055); }
.card h3 { margin: 14px 0 9px; font-size: 1.2rem; }
.card p { margin: 0; color: var(--muted); }
.icon { display: grid; place-items: center; width: 42px; height: 42px; border-radius: 12px; color: var(--blue-dark); background: #eaf1ff; font: 750 1rem/1 ui-monospace, SFMono-Regular, Menlo, monospace; }
.band { padding: 34px; border-radius: 24px; color: white; background: #111c35; display: flex; justify-content: space-between; align-items: center; gap: 28px; }
.band h2 { font-size: clamp(1.65rem, 3vw, 2.4rem); }
.band p { max-width: 650px; color: #cbd5e1; margin: 10px 0 0; }

.page-hero { padding: 78px 0 48px; background: white; border-bottom: 1px solid var(--line); }
.page-hero h1 { font-size: clamp(2.5rem, 5vw, 4.2rem); }
.content { width: min(820px, calc(100% - 40px)); margin: 0 auto; padding: 58px 0 86px; }
.content h2 { margin: 44px 0 12px; font-size: 1.55rem; }
.content h2:first-child { margin-top: 0; }
.content p, .content li { color: #3f4b5a; }
.content ul { padding-left: 22px; }
.notice { padding: 20px 22px; border: 1px solid #bfdbfe; border-radius: 16px; background: #eff6ff; color: #1e3a8a; }
.faq { border-top: 1px solid var(--line); }
.faq details { border-bottom: 1px solid var(--line); padding: 18px 0; }
.faq summary { cursor: pointer; font-weight: 720; color: var(--ink); }
.faq details p { margin-bottom: 0; }

footer { padding: 30px 0 44px; border-top: 1px solid var(--line); color: #64748b; }
.footer-row { display: flex; justify-content: space-between; gap: 24px; flex-wrap: wrap; }
.footer-links { display: flex; gap: 20px; flex-wrap: wrap; }
.footer-links a { color: #475569; }

@media (max-width: 820px) {
  .hero { padding-top: 72px; }
  .hero-grid { grid-template-columns: 1fr; gap: 38px; }
  .graph-card { min-height: 310px; }
  .cards { grid-template-columns: 1fr; }
  .band { align-items: flex-start; flex-direction: column; }
}

@media (max-width: 560px) {
  .shell, .content { width: min(100% - 28px, 1120px); }
  .nav { min-height: 64px; }
  .nav-links { gap: 13px; font-size: .9rem; }
  .nav-links a:first-child { display: none; }
  .hero { padding: 60px 0 56px; }
  .graph-card { min-height: 280px; border-radius: 22px; }
  .section { padding: 58px 0; }
}

@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }