:root {
  --background: #f5f5f7;
  --surface: #ffffff;
  --surface-soft: #f8f9fb;
  --text: #1d1d1f;
  --muted: #5f6368;
  --primary: #007aff;
  --primary-hover: #0062cc;
  --border: #e5e5ea;
  --warning-bg: #fff7e6;
  --warning-border: #f2b84b;
  --max-width: 1040px;
  --radius: 20px;
  --shadow: 0 10px 35px rgba(0, 0, 0, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
  color: var(--text);
  background: var(--background);
  line-height: 1.6;
}

a {
  color: var(--primary);
}

a:hover {
  color: var(--primary-hover);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  border-bottom: 1px solid rgba(229, 229, 234, 0.9);
  background: rgba(245, 245, 247, 0.92);
  backdrop-filter: blur(18px);
}

.nav {
  width: min(calc(100% - 32px), var(--max-width));
  margin: 0 auto;
  min-height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  color: var(--text);
  font-size: 1.2rem;
  font-weight: 800;
  text-decoration: none;
}

.nav-links {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 18px;
}

.nav-links a {
  color: var(--muted);
  font-weight: 600;
  text-decoration: none;
}

.nav-links a:hover,
.nav-links a[aria-current="page"] {
  color: var(--primary);
}

.container {
  width: min(calc(100% - 32px), var(--max-width));
  margin: 0 auto;
}

.hero {
  padding: 86px 0 52px;
  text-align: center;
}

.hero-card,
.content-card {
  background: var(--surface);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.hero-card {
  padding: 72px 32px;
}

.eyebrow {
  margin: 0 0 12px;
  color: var(--primary);
  font-size: 0.85rem;
  font-weight: 800;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

h1 {
  margin: 0 0 18px;
  font-size: clamp(2.6rem, 8vw, 5rem);
  line-height: 1.02;
  letter-spacing: -0.04em;
}

h2 {
  margin-top: 0;
  font-size: clamp(1.7rem, 4vw, 2.4rem);
  line-height: 1.2;
}

h3 {
  margin-bottom: 8px;
  line-height: 1.3;
}

.lead {
  max-width: 680px;
  margin: 0 auto 30px;
  color: var(--muted);
  font-size: 1.18rem;
}

.actions {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 12px;
}

.button {
  display: inline-block;
  padding: 14px 22px;
  border: 0;
  border-radius: 12px;
  background: var(--primary);
  color: #fff;
  font-weight: 800;
  text-decoration: none;
}

.button:hover {
  background: var(--primary-hover);
  color: #fff;
}

.button.secondary {
  border: 1px solid var(--border);
  background: var(--surface-soft);
  color: var(--text);
}

.section {
  padding: 28px 0 54px;
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.feature {
  padding: 26px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: var(--surface);
}

.feature p {
  margin-bottom: 0;
  color: var(--muted);
}

.page {
  padding: 54px 0 72px;
}

.content-card {
  padding: clamp(26px, 5vw, 56px);
}

.content-card > :first-child {
  margin-top: 0;
}

.content-card p,
.content-card li {
  color: #42454a;
}

.content-card h2 {
  margin-top: 42px;
  padding-top: 8px;
  border-top: 1px solid var(--border);
}

.content-card h3 {
  margin-top: 28px;
}

.content-card ul,
.content-card ol {
  padding-left: 22px;
}

.notice {
  margin: 24px 0;
  padding: 18px 20px;
  border-left: 4px solid var(--warning-border);
  border-radius: 10px;
  background: var(--warning-bg);
}

.placeholder {
  padding: 0.08em 0.3em;
  border-radius: 4px;
  background: #fff0f0;
  color: #a40000;
  font-weight: 800;
}

.definition-list {
  display: grid;
  grid-template-columns: minmax(150px, 220px) 1fr;
  gap: 10px 24px;
}

.definition-list dt {
  font-weight: 800;
}

.definition-list dd {
  margin: 0;
  color: var(--muted);
}

.faq details {
  padding: 18px 0;
  border-bottom: 1px solid var(--border);
}

.faq summary {
  cursor: pointer;
  font-weight: 800;
}

.faq details p {
  margin-bottom: 0;
}

.site-footer {
  padding: 20px 0 42px;
  color: #74777c;
  font-size: 0.92rem;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 14px 24px;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

.footer-links a {
  color: inherit;
}

@media (max-width: 760px) {
  .nav {
    align-items: flex-start;
    flex-direction: column;
    padding: 15px 0;
    gap: 10px;
  }

  .nav-links {
    gap: 10px 16px;
  }

  .hero {
    padding-top: 42px;
  }

  .hero-card {
    padding: 52px 22px;
  }

  .grid {
    grid-template-columns: 1fr;
  }

  .definition-list {
    grid-template-columns: 1fr;
    gap: 2px;
  }

  .definition-list dd {
    margin-bottom: 14px;
  }
}