:root {
  --color-primary: #0066cc;
  --color-primary-hover: #0052a3;
  --color-ink: #111827;
  --color-slate: #4b5563;
  --color-mist: #d6dce5;
  --color-cloud: #f7f9fc;
  --color-paper: #ffffff;
  --color-midnight: #0b1020;
  --color-surface-dark: #121826;
  --color-ice: #e5eef9;
  --radius: 8px;
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-5: 48px;
  --space-6: 64px;
  --shadow-soft: 0 14px 32px rgba(17, 24, 39, 0.08);
  --max-width: 1120px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Noto Sans JP", system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
  color: var(--color-ink);
  background:
    radial-gradient(circle at top right, rgba(0, 102, 204, 0.08), transparent 28%),
    linear-gradient(180deg, #f9fbff 0%, #f7f9fc 100%);
}

a {
  color: inherit;
  text-decoration: none;
}

.page-shell {
  min-height: 100vh;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: var(--space-2);
  width: min(calc(100% - 32px), var(--max-width));
  margin: 0 auto;
  padding: 20px 0;
  transition: padding 180ms ease, background-color 180ms ease, backdrop-filter 180ms ease;
}

.site-header[data-scrolled="true"] {
  padding: 12px var(--space-2);
  margin-top: var(--space-2);
  border: 1px solid rgba(214, 220, 229, 0.92);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.82);
  backdrop-filter: blur(16px);
}

.brand {
  font-weight: 800;
  letter-spacing: -0.02em;
}

.site-nav {
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
}

.site-nav a {
  color: var(--color-slate);
  font-size: 14px;
}

.site-nav a:hover,
.social-link:hover,
.text-link:hover {
  color: var(--color-primary);
}

main {
  width: min(calc(100% - 32px), var(--max-width));
  margin: 0 auto;
  padding-bottom: var(--space-6);
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) minmax(280px, 420px);
  gap: var(--space-4);
  align-items: stretch;
  padding: var(--space-5) 0 var(--space-4);
}

.hero-copy,
.hero-panel,
.surface-card,
.feature-card,
.stack-card,
.faq-item {
  border: 1px solid var(--color-mist);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.86);
  box-shadow: var(--shadow-soft);
}

.hero-copy {
  padding: var(--space-5);
}

.hero-panel {
  padding: var(--space-4);
  background:
    linear-gradient(180deg, rgba(11, 16, 32, 0.98), rgba(18, 24, 38, 0.96));
  color: var(--color-ice);
  border-color: #273244;
}

.eyebrow,
.panel-label,
.affiliate-meta {
  margin: 0 0 var(--space-2);
  color: var(--color-primary);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.panel-label {
  color: #8bbcf1;
}

h1,
h2,
h3 {
  margin: 0;
  letter-spacing: -0.03em;
}

h1 {
  font-size: clamp(36px, 6vw, 56px);
  line-height: 1.05;
}

h2 {
  font-size: clamp(28px, 4vw, 38px);
  line-height: 1.14;
}

h3 {
  font-size: 20px;
  line-height: 1.25;
}

p,
li,
summary {
  font-size: 15px;
  line-height: 1.7;
}

.hero-description,
.footer-copy,
.feature-card p,
.stack-card p,
.surface-card p,
.faq-item p {
  color: var(--color-slate);
}

.hero-description {
  margin: var(--space-3) 0 0;
  font-size: 17px;
  max-width: 56ch;
}

.hero-actions {
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
  margin-top: var(--space-4);
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 var(--space-3);
  border-radius: var(--radius);
  border: 1px solid transparent;
  font-weight: 700;
  transition: transform 160ms ease, background-color 160ms ease, border-color 160ms ease;
}

.button:hover {
  transform: translateY(-1px);
}

.button.primary {
  background: var(--color-primary);
  color: var(--color-paper);
}

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

.button.secondary {
  border-color: var(--color-mist);
  background: var(--color-paper);
}

.highlight-list,
.checklist {
  margin: 0;
  padding: 0;
  list-style: none;
}

.highlight-list li {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: var(--space-2) 0;
  border-bottom: 1px solid rgba(39, 50, 68, 0.72);
}

.highlight-list li:last-child {
  border-bottom: 0;
}

.highlight-list span {
  flex: 0 0 10px;
  width: 10px;
  height: 10px;
  margin-top: 8px;
  border-radius: 999px;
  background: #66a3e0;
}

.section {
  padding: var(--space-5) 0 0;
}

.section-heading {
  max-width: 720px;
  margin-bottom: var(--space-3);
}

.feature-grid,
.stack-grid,
.monetize-grid {
  display: grid;
  gap: var(--space-3);
}

.feature-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.stack-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.monetize-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.feature-card,
.stack-card,
.surface-card {
  padding: var(--space-3);
}

.stack-section .stack-card:nth-child(2) {
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.96), rgba(240, 246, 255, 0.96));
}

.affiliate-disclosure {
  margin-top: var(--space-1);
}

.affiliate-grid {
  display: grid;
  gap: var(--space-2);
  margin-top: var(--space-3);
}

.affiliate-card,
.notice-card,
.adsense-card {
  padding: var(--space-2);
  border-radius: var(--radius);
  border: 1px solid var(--color-mist);
  background: var(--color-paper);
}

.checklist {
  display: grid;
  gap: var(--space-2);
  counter-reset: item;
}

.checklist li {
  display: flex;
  gap: var(--space-2);
  align-items: flex-start;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius);
  border: 1px solid var(--color-mist);
  background: rgba(255, 255, 255, 0.88);
}

.checklist li::before {
  counter-increment: item;
  content: counter(item);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: 999px;
  background: rgba(0, 102, 204, 0.12);
  color: var(--color-primary);
  font-size: 14px;
  font-weight: 800;
  flex: 0 0 28px;
}

.faq-list {
  display: grid;
  gap: var(--space-2);
}

.faq-item {
  padding: 0 var(--space-3);
}

.faq-item summary {
  cursor: pointer;
  padding: var(--space-3) 0;
  font-weight: 700;
  list-style: none;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item p {
  margin: 0 0 var(--space-3);
}

.site-footer {
  display: grid;
  gap: var(--space-2);
  width: min(calc(100% - 32px), var(--max-width));
  margin: 0 auto;
  padding: var(--space-5) 0 var(--space-4);
}

.footer-title {
  margin: 0;
  font-size: 16px;
  font-weight: 800;
}

.footer-links {
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
}

.social-link,
.text-link {
  color: var(--color-primary);
  font-weight: 700;
}

@media (max-width: 960px) {
  .hero,
  .feature-grid,
  .stack-grid,
  .monetize-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 720px) {
  .site-header,
  .site-header[data-scrolled="true"] {
    width: calc(100% - 24px);
    border-radius: 24px;
  }

  .hero-copy,
  .hero-panel {
    padding: var(--space-3);
  }

  .site-nav {
    display: none;
  }

  main,
  .site-footer {
    width: calc(100% - 24px);
  }

  .hero {
    padding-top: var(--space-4);
  }
}