:root {
  --bg: #f7f8fb;
  --text: #0f172a;
  --muted: #6b7280;
  --card: #ffffff;
  --accent: #2563eb;
  --accent-2: #7c3aed;
  --border: #e5e7eb;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Inter", "Noto Sans JP", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: radial-gradient(circle at 20% 20%, #f6f8ff, #f7f8fb 25%),
    radial-gradient(circle at 80% 0%, #f0f8ff, #f7f8fb 30%),
    linear-gradient(180deg, #ffffff 0%, #f7f8fb 100%);
  color: var(--text);
  min-height: 100vh;
}

.page {
  width: 100%;
  max-width: 1080px;
  margin: 0 auto;
  padding: 96px 18px 64px;
}

.content-card {
  background: var(--card);
  border-radius: 20px;
  padding: 32px;
  box-shadow: 0 20px 60px rgba(15, 23, 42, 0.12);
  border: 1px solid rgba(255, 255, 255, 0.6);
  backdrop-filter: blur(4px);
}

.section-title {
  font-size: 22px;
  margin: 0 0 10px;
}

.section-subtitle {
  color: var(--muted);
  margin-bottom: 18px;
  font-size: 14px;
}

.button-row {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 16px;
  border-radius: 12px;
  font-weight: 600;
  border: 1px solid transparent;
  color: #fff;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  text-decoration: none;
  transition: transform 0.18s ease, box-shadow 0.18s ease;
}

.btn.secondary {
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 25px rgba(37, 99, 235, 0.25);
}

.grid {
  display: grid;
  gap: 18px;
}

.grid.two {
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.card-link {
  display: block;
  text-decoration: none;
  color: inherit;
  background: var(--card);
  border-radius: 16px;
  padding: 20px;
  border: 1px solid var(--border);
  transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
}

.card-link:hover {
  transform: translateY(-4px);
  border-color: rgba(37, 99, 235, 0.4);
  box-shadow: 0 12px 30px rgba(15, 23, 42, 0.1);
}

.card-link h3 {
  margin: 0 0 6px;
  font-size: 18px;
}

.card-link p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.6;
}

.hero {
  padding: 32px;
  background: linear-gradient(135deg, rgba(37, 99, 235, 0.08), rgba(124, 58, 237, 0.08));
  border-radius: 24px;
  border: 1px solid rgba(37, 99, 235, 0.15);
  text-align: left;
  display: grid;
  gap: 12px;
}

.pill {
  display: inline-flex;
  align-items: center;
  padding: 8px 12px;
  border-radius: 999px;
  background: rgba(37, 99, 235, 0.12);
  color: var(--accent);
  font-weight: 700;
  font-size: 12px;
  width: fit-content;
}

.hero h1 {
  margin: 0;
  font-size: 30px;
}

.hero p {
  margin: 0;
  color: var(--muted);
  line-height: 1.7;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  width: 100%;
  background: rgba(255, 255, 255, 0.75);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(226, 232, 240, 0.8);
  transition: transform 0.22s ease, background 0.22s ease, box-shadow 0.22s ease;
}

.site-header.header-hidden {
  transform: translateY(-100%);
}

.site-header.scrolled {
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
  background: rgba(255, 255, 255, 0.95);
}

.header-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 14px 18px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  letter-spacing: 0.3px;
}

.brand .title {
  font-size: 18px;
}

.brand .subtitle {
  font-size: 11px;
  color: var(--muted);
}

.nav-links {
  display: flex;
  gap: 14px;
  align-items: center;
}

.nav-links a {
  color: var(--text);
  text-decoration: none;
  font-weight: 600;
  padding: 8px 12px;
  border-radius: 10px;
  transition: background 0.18s ease, color 0.18s ease;
}

.nav-links a:hover {
  background: rgba(37, 99, 235, 0.08);
  color: var(--accent);
}

.menu-toggle {
  display: none;
  background: transparent;
  border: none;
  width: 40px;
  height: 40px;
  border-radius: 12px;
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

.menu-toggle span,
.menu-toggle::before,
.menu-toggle::after {
  display: block;
  width: 18px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.menu-toggle::before,
.menu-toggle::after {
  content: "";
  position: relative;
}

.menu-toggle::before {
  top: -6px;
}

.menu-toggle::after {
  top: 6px;
}

body.nav-open .menu-toggle span {
  opacity: 0;
}

body.nav-open .menu-toggle::before {
  transform: translateY(6px) rotate(45deg);
}

body.nav-open .menu-toggle::after {
  transform: translateY(-6px) rotate(-45deg);
}

.mobile-nav {
  display: none;
}

@media (max-width: 720px) {
  .header-inner {
    padding: 12px 14px;
  }

  .nav-links {
    display: none;
  }

  .menu-toggle {
    display: inline-flex;
  }

  body.nav-open .mobile-nav {
    display: block;
  }

  .mobile-nav {
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.97);
    border-bottom: 1px solid rgba(226, 232, 240, 0.9);
    box-shadow: 0 14px 36px rgba(15, 23, 42, 0.12);
  }

  .mobile-nav a {
    display: block;
    padding: 12px 16px;
    color: var(--text);
    text-decoration: none;
    border-top: 1px solid rgba(226, 232, 240, 0.8);
    font-weight: 600;
  }

  .mobile-nav a:hover {
    background: rgba(37, 99, 235, 0.06);
  }

  .page {
    padding: 82px 14px 52px;
  }

  .hero {
    padding: 22px;
  }
}

.article {
  display: grid;
  gap: 14px;
  line-height: 1.7;
  color: var(--text);
}

.article h1 {
  margin: 0;
  font-size: 28px;
}

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

.divider {
  height: 1px;
  background: linear-gradient(90deg, rgba(37, 99, 235, 0), rgba(37, 99, 235, 0.6), rgba(37, 99, 235, 0));
  margin: 12px 0 4px;
}

.markdown {
  font-size: 15px;
  line-height: 1.7;
  color: var(--text);
}

.markdown h1,
.markdown h2,
.markdown h3 {
  margin-top: 22px;
  margin-bottom: 8px;
}

.markdown h2 {
  border-bottom: 1px solid var(--border);
  padding-bottom: 4px;
}

.markdown ul {
  padding-left: 1.1em;
}

.footer {
  margin-top: 26px;
  text-align: center;
  color: var(--muted);
  font-size: 12px;
}