*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

:root {
  --ink: #171717;
  --body: #4d4d4d;
  --muted: #888888;
  --hairline: #ebebeb;
  --hairline-2: #e2e2e2;
  --hairline-strong: #a1a1a1;
  --canvas: #ffffff;
  --canvas-soft: #fafafa;
  --link: #0070f3;
  --font: 'Geist', Inter, system-ui, -apple-system, sans-serif;
  --mono: 'Geist Mono', ui-monospace, SFMono-Regular, Menlo, monospace;
  --maxw: 1100px;
  --pad: clamp(72px, 11vh, 128px);
  --shadow-2: 0 1px 1px rgba(0,0,0,0.02), 0 2px 2px rgba(0,0,0,0.04), inset 0 0 0 1px rgba(0,0,0,0.06);
  --shadow-3: 0 2px 2px rgba(0,0,0,0.03), 0 8px 12px -8px rgba(0,0,0,0.08), inset 0 0 0 1px rgba(0,0,0,0.06);
}

html { scroll-behavior: smooth; }
body {
  font-family: var(--font);
  background: var(--canvas-soft);
  color: var(--ink);
  -webkit-font-smoothing: antialiased;
  font-feature-settings: "ss01", "cv01";
  line-height: 1.5;
  letter-spacing: -0.011em;
}
::selection { background: var(--ink); color: #f2f2f2; }

.wrap { max-width: var(--maxw); margin: 0 auto; padding-left: 24px; padding-right: 24px; }

/* ── progress bar ── */
#progress {
  position: fixed; top: 0; left: 0; height: 2px; width: 0;
  background: var(--ink); z-index: 200; transition: width .12s linear;
}

/* ── nav ── */
.site-nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  height: 64px; display: flex; align-items: center;
  border-bottom: 1px solid transparent;
  transition: background .3s, border-color .3s, backdrop-filter .3s;
}
.site-nav.scrolled {
  background: rgba(250,250,250,0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-color: var(--hairline);
}
.site-nav .wrap { display: flex; align-items: center; justify-content: space-between; width: 100%; }
.nav-brand img { height: 48px; width: auto; display: block; mix-blend-mode: multiply; }
.nav-right { display: flex; align-items: center; gap: 20px; }
.nav-link {
  font-size: 14px; letter-spacing: -0.02em;
  color: var(--body); text-decoration: none;
  transition: color .15s;
}
.nav-link:hover { color: var(--ink); }

/* dropdown */
.nav-dropdown { position: relative; }
.nav-dropdown-toggle {
  display: flex; align-items: center; gap: 4px;
  cursor: pointer; background: none; border: none; padding: 0;
  font-family: var(--font);
}
.nav-dropdown-toggle svg { transition: transform .2s; }
.nav-dropdown.open .nav-dropdown-toggle svg { transform: rotate(180deg); }
.nav-dropdown-menu {
  position: absolute; top: calc(100% + 12px); left: 50%;
  transform: translateX(-50%) translateY(-6px);
  background: #fff; border: 1px solid var(--hairline);
  border-radius: 12px; box-shadow: var(--shadow-3);
  padding: 6px; min-width: 230px;
  opacity: 0; pointer-events: none;
  transition: opacity .18s, transform .18s;
}
.nav-dropdown.open .nav-dropdown-menu {
  opacity: 1; pointer-events: auto;
  transform: translateX(-50%) translateY(0);
}
.nav-dropdown-item {
  display: block; padding: 10px 14px;
  font-size: 14px; letter-spacing: -0.02em;
  color: var(--body); text-decoration: none;
  border-radius: 8px; transition: background .12s, color .12s;
}
.nav-dropdown-item:hover { background: var(--canvas-soft); color: var(--ink); }
.nav-dropdown-item strong { display: block; color: var(--ink); font-weight: 500; margin-bottom: 2px; }
.nav-dropdown-item span { font-size: 12px; color: var(--muted); }
.nav-dropdown-item.current strong { font-weight: 700; }
.nav-dropdown-item.current { color: var(--ink); }

/* btn */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  gap: 8px; font-family: var(--font); font-weight: 500;
  text-decoration: none; cursor: pointer; border-radius: 100px;
  transition: background .2s, color .2s, border-color .2s, transform .15s;
  white-space: nowrap;
}
.btn-primary {
  background: var(--ink); color: #fff;
  font-size: 14px; padding: 0 18px; height: 36px;
  border: 1px solid var(--ink);
}
.btn-primary:hover { background: #000; transform: translateY(-1px); }

@media (max-width: 640px) { .nav-right .nav-dropdown, .nav-right .btn { display: none; } }

/* ── hero ── */
.hero {
  position: relative; padding: 168px 0 48px; overflow: hidden; text-align: center;
  background:
    radial-gradient(82% 72% at 8% -12%, rgba(0,124,240,0.40), transparent 66%),
    radial-gradient(80% 70% at 92% -12%, rgba(34,205,158,0.40), transparent 66%),
    radial-gradient(72% 62% at 50% -16%, rgba(120,140,250,0.24), transparent 64%);
}
.hero .wrap { position: relative; z-index: 1; }

.eyebrow {
  font-family: var(--mono); font-size: 12px; font-weight: 400;
  letter-spacing: 0.04em; color: var(--muted); text-transform: uppercase;
}

h1 {
  max-width: 820px; margin: 16px auto 20px;
  font-size: clamp(40px, 6.4vw, 72px);
  line-height: 1.02; letter-spacing: -0.045em; font-weight: 600;
}

.hero .lead {
  max-width: 580px; margin: 0 auto 36px;
  color: var(--body);
  font-size: clamp(17px, 1.6vw, 20px);
  line-height: 1.55; letter-spacing: -0.012em;
}

.cta {
  display: inline-flex; align-items: center;
  height: 48px; padding: 0 22px;
  border: 1px solid var(--ink); border-radius: 100px;
  background: var(--ink); color: #fff;
  font-family: var(--font); font-weight: 500;
  font-size: 15px; text-decoration: none; letter-spacing: -0.01em;
  transition: background .2s, transform .15s;
}
.cta:hover { background: #000; transform: translateY(-1px); }

/* ── content ── */
main { padding-top: 24px; padding-bottom: 96px; }

.sections { }

.section {
  padding: 40px 0;
  border-top: 1px solid var(--hairline-2);
}
.section:last-child { border-bottom: 1px solid var(--hairline-2); }

h2 {
  margin: 0 0 14px;
  font-size: clamp(22px, 3vw, 32px);
  line-height: 1.1; letter-spacing: -0.035em; font-weight: 600;
}

.section p {
  max-width: 720px; color: var(--body);
  font-size: 17px; line-height: 1.65;
}

/* ── guide-nav ── */
.guide-nav {
  margin-top: 72px; padding-top: 28px;
  border-top: 1px solid var(--hairline-2);
  display: flex; align-items: center; gap: 24px; flex-wrap: wrap;
}
.guide-nav strong {
  font-size: 13px; font-weight: 600; letter-spacing: -0.01em; color: var(--ink);
  white-space: nowrap;
}
.guide-nav a {
  font-size: 14px; letter-spacing: -0.01em;
  color: var(--body); text-decoration: none;
  transition: color .15s;
}
.guide-nav a:hover { color: var(--ink); }
.guide-nav a.current { color: var(--ink); font-weight: 700; }

/* ── footer ── */
.site-footer {
  padding: 28px 0;
  border-top: 1px solid var(--hairline-2);
  background: var(--canvas);
}
.site-footer .wrap { display: flex; align-items: center; justify-content: space-between; gap: 16px; }
.site-footer span {
  font-family: var(--mono); font-size: 12px; color: var(--muted);
}
.site-footer a {
  font-size: 13px; color: var(--body); text-decoration: none;
  transition: color .15s;
}
.site-footer a:hover { color: var(--ink); }

@media (max-width: 560px) {
  .hero { padding: 128px 0 64px; }
  .section { padding: 28px 0; }
  .guide-nav { align-items: flex-start; flex-direction: column; gap: 12px; }
  .site-footer .wrap { flex-direction: column; align-items: flex-start; gap: 8px; }
}