.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: var(--line-thin) solid transparent;
  transition: background var(--duration-fast) ease, border-color var(--duration-fast) ease, backdrop-filter var(--duration-fast) ease;
}

.site-header.is-scrolled {
  background: var(--header-blur-bg);
  border-bottom-color: var(--border-subtle);
  backdrop-filter: blur(12px);
}

.container {
  width: min(var(--container-max), 100% - (var(--container-px) * 2));
  margin-inline: auto;
}

.header-inner {
  min-height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-6);
}

.brand {
  display: inline-flex;
  flex-direction: column;
  gap: var(--space-1);
}

.brand-main {
  font-size: var(--text-sm);
  letter-spacing: 0.12em;
  font-weight: 700;
}

.brand-sub {
  font-size: var(--text-xs);
  color: var(--text-tertiary);
  letter-spacing: 0.08em;
}

.nav {
  position: fixed;
  inset: 0;
  background: var(--bg-base);
  display: none;
  align-items: center;
  justify-content: center;
}

.nav.is-open {
  display: flex;
}

.nav-list {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-8);
}

.nav-link {
  font-size: var(--text-h2);
  color: var(--text-secondary);
  transition: color var(--duration-fast) ease;
}

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

.header-cta {
  display: none;
}

.nav-cta-item {
  margin-top: var(--space-4);
}

.menu-toggle {
  border: var(--line-thin) solid var(--border-default);
  background: var(--bg-subtle);
  color: var(--text-primary);
  border-radius: var(--radius-sm);
  width: var(--menu-size);
  height: var(--menu-size);
  padding: 0;
  display: grid;
  place-items: center;
}

.menu-toggle-line {
  width: var(--menu-line-width);
  height: var(--line-thin);
  background: var(--text-primary);
  display: block;
  position: relative;
}

.menu-toggle-line::before,
.menu-toggle-line::after {
  content: "";
  position: absolute;
  left: 0;
  width: var(--menu-line-width);
  height: var(--line-thin);
  background: var(--text-primary);
}

.menu-toggle-line::before {
  top: calc(var(--menu-line-offset) * -1);
}

.menu-toggle-line::after {
  top: var(--menu-line-offset);
}

.menu-toggle[aria-expanded="true"] .menu-toggle-line {
  background: transparent;
}

.menu-toggle[aria-expanded="true"] .menu-toggle-line::before {
  top: 0;
  transform: rotate(45deg);
}

.menu-toggle[aria-expanded="true"] .menu-toggle-line::after {
  top: 0;
  transform: rotate(-45deg);
}

@media (max-width: 768px) {
  .site-main > .section:first-child {
    padding-top: var(--space-8);
  }

  .header-actions {
    display: flex;
    align-items: center;
    gap: var(--space-2);
  }

  .header-cta {
    display: inline-flex;
    order: 1;
    min-height: 40px;
    padding-inline: var(--space-4);
    font-size: var(--text-sm);
  }

  .menu-toggle {
    order: 2;
  }
}

.site-main {
  overflow: hidden;
}

.section {
  padding-block: var(--section-py);
}

.section-alt {
  background: var(--bg-elevated);
}

.grid {
  display: grid;
  gap: var(--space-8);
}

.site-footer {
  border-top: var(--line-thin) solid var(--border-subtle);
  padding-top: var(--space-16);
  padding-bottom: var(--space-8);
}

.footer-grid {
  display: grid;
  gap: var(--space-12);
}

.footer-links {
  display: grid;
  gap: var(--space-3);
}

.footer-copy {
  margin-top: var(--space-16);
  padding-top: var(--space-6);
  border-top: var(--line-thin) solid var(--border-subtle);
  font-size: var(--text-xs);
  color: var(--text-tertiary);
}

@media (min-width: 768px) {
  .nav {
    position: static;
    inset: auto;
    background: transparent;
    display: block;
  }

  .nav-list {
    flex-direction: row;
    gap: var(--space-6);
  }

  .nav-link {
    font-size: var(--text-sm);
  }

  .nav-cta-item {
    display: none;
  }

  .menu-toggle {
    display: none;
  }

  .header-cta {
    display: inline-flex;
  }

  .header-actions {
    display: flex;
    align-items: center;
    gap: var(--space-4);
  }

  .footer-grid {
    grid-template-columns: 1.2fr 1fr 1.2fr;
  }
}

@media (min-width: 1280px) {
  .header-inner {
    min-height: var(--header-height-lg);
  }
}