* {
  box-sizing: border-box;
}

body {
  margin: 0;
  color: #1d1f23;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.65;
  background: #f6f8fc;
}

a {
  color: inherit;
}

.seo-header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  gap: 24px;
  align-items: center;
  justify-content: space-between;
  padding: 16px clamp(20px, 5vw, 72px);
  background: rgba(255, 255, 255, 0.94);
  border-bottom: 1px solid #e3eaf5;
  backdrop-filter: blur(10px);
}

.seo-logo {
  color: #18316c;
  font-weight: 800;
  text-decoration: none;
}

.seo-header nav,
.seo-related {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.seo-header nav a,
.seo-related a,
.seo-actions a {
  display: inline-flex;
  align-items: center;
  min-height: 36px;
  padding: 8px 12px;
  color: #18316c;
  font-weight: 600;
  border: 1px solid #e3eaf5;
  border-radius: 6px;
  text-decoration: none;
  background: #fff;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.seo-header nav a:hover,
.seo-related a:hover {
  border-color: #18316c;
  box-shadow: 0 2px 12px rgba(24, 49, 108, 0.08);
}

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

.seo-hero {
  padding: clamp(52px, 8vw, 96px) 0 44px;
}

.seo-hero p {
  margin: 0 0 12px;
  color: #1e4e9c;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.seo-hero h1 {
  margin: 0;
  color: #18316c;
  font-size: clamp(34px, 5vw, 62px);
  font-weight: 700;
  line-height: 1.12;
  letter-spacing: -0.01em;
}

.seo-hero strong {
  display: block;
  max-width: 760px;
  margin-top: 18px;
  color: #4a5160;
  font-size: clamp(18px, 2vw, 23px);
  font-weight: 500;
}

.seo-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 28px;
}

.seo-actions a:first-child {
  color: #fff;
  border-color: #18316c;
  background: #18316c;
}

.seo-actions a:first-child:hover {
  border-color: #1e4e9c;
  background: #1e4e9c;
  box-shadow: 0 4px 16px rgba(24, 49, 108, 0.18);
}

.seo-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}

.seo-grid > div,
.seo-section {
  padding: 28px;
  background: #fff;
  border: 1px solid #e3eaf5;
  border-radius: 8px;
}

h2 {
  margin: 0 0 14px;
  color: #18316c;
  font-size: 24px;
  font-weight: 700;
  letter-spacing: -0.01em;
}

ul {
  margin: 0;
  padding-left: 20px;
}

dl {
  margin: 0;
}

dt {
  margin-top: 12px;
  color: #18316c;
  font-weight: 700;
}

dd {
  margin: 4px 0 0;
}

.seo-section {
  margin-top: 18px;
}

details {
  padding: 16px 0;
  border-top: 1px solid #e3eaf5;
}

details:first-of-type {
  border-top: 0;
  padding-top: 0;
}

summary {
  cursor: pointer;
  color: #18316c;
  font-weight: 600;
}

summary + p {
  margin: 10px 0 0;
  color: #4a5160;
}

footer {
  margin-top: 48px;
  padding: 28px 20px;
  color: #59616b;
  text-align: center;
  border-top: 1px solid #e3eaf5;
}

@media (max-width: 760px) {
  .seo-header {
    position: static;
    align-items: flex-start;
    flex-direction: column;
  }

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