.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: rgba(247, 248, 255, 0.92);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(148, 163, 184, 0.25);
}

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-4);
  padding-bottom: var(--space-4);
  gap: var(--space-6);
}

.header__brand {
  display: flex;
  align-items: center;
  min-width: 0;
}

.header__logo-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-4);
  color: var(--color-accent-navy);
}

.header__logo-mark {
  display: inline-grid;
  grid-template-columns: repeat(2, 10px);
  grid-template-rows: repeat(2, 10px);
  gap: 3px;
  padding: 6px;
  border-radius: var(--radius-lg);
  background: #ffffff;
  box-shadow: var(--shadow-sm);
}

.header__logo-block {
  width: 10px;
  height: 10px;
  border-radius: 3px;
}

.header__logo-block--blue { background: var(--color-primary); }
.header__logo-block--yellow { background: var(--color-accent-yellow); }
.header__logo-block--purple { background: var(--color-accent-purple); }

.header__brand-text {
  display: flex;
  flex-direction: column;
}

.header__brand-title {
  font-family: var(--font-display);
  font-size: var(--font-size-lg);
  font-weight: 700;
  letter-spacing: -0.02em;
}

.header__brand-tagline {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
}

.header__nav {
  margin-left: auto;
}

.header__nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-6);
  list-style: none;
}

.header__nav-item--highlight .header__nav-link {
  padding: 6px 14px;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--color-accent-yellow), #ffeaa7);
  color: var(--color-accent-navy);
  font-weight: 600;
}

.header__nav-link {
  position: relative;
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text-muted);
  padding: 4px 0;
}

.header__nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -4px;
  width: 0;
  height: 2px;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent-purple));
  transition: width var(--transition-base);
}

.header__nav-link:hover::after,
.header__nav-item.is-active .header__nav-link::after {
  width: 100%;
}

.header__nav-item.is-active .header__nav-link {
  color: var(--color-accent-navy);
}

.header__nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  border-radius: 999px;
  border: 1px solid rgba(148, 163, 184, 0.6);
  background: #ffffff;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 4px;
  cursor: pointer;
}

.header__nav-toggle-bar {
  width: 18px;
  height: 2px;
  border-radius: 999px;
  background: var(--color-accent-navy);
  transition: transform var(--transition-base), opacity var(--transition-base), translate var(--transition-base);
}

.header__nav-toggle.is-open .header__nav-toggle-bar:nth-child(1) {
  transform: rotate(45deg) translate(3px, 3px);
}

.header__nav-toggle.is-open .header__nav-toggle-bar:nth-child(2) {
  opacity: 0;
}

.header__nav-toggle.is-open .header__nav-toggle-bar:nth-child(3) {
  transform: rotate(-45deg) translate(3px, -3px);
}

@media (max-width: 960px) {
  .header__nav-toggle {
    display: inline-flex;
  }

  .header__nav {
    position: fixed;
    inset: 64px 0 auto 0;
    z-index: 39;
    max-height: 0;
    overflow: hidden;
    background: rgba(247, 248, 255, 0.98);
    border-bottom: 1px solid rgba(148, 163, 184, 0.25);
    transition: max-height var(--transition-slow);
  }

  .header__nav.is-open {
    max-height: 320px;
  }

  .header__nav-list {
    flex-direction: column;
    align-items: flex-start;
    padding: var(--space-6) var(--space-8);
    gap: var(--space-4);
  }

  .header__nav-item--highlight .header__nav-link {
    align-self: stretch;
    text-align: center;
  }
}

@media (max-width: 600px) {
  .header__brand-title {
    font-size: var(--font-size-base);
  }

  .header__brand-tagline {
    display: none;
  }
}