.site-header {
  position: sticky;
  top: 0;
  background:
    linear-gradient(110deg, rgba(255, 255, 255, 0.07), transparent 28%),
    radial-gradient(circle at 72% -120%, rgba(46, 91, 204, 0.72), transparent 52%),
    linear-gradient(115deg, #090b12 0%, #111827 48%, #081735 100%);
  box-shadow:
    inset 0 1px rgba(255, 255, 255, 0.1),
    inset 0 -1px rgba(227, 206, 161, 0.18),
    0 14px 35px rgba(14, 14, 13, 0.15);
  isolation: isolate;
}

.site-header::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background: linear-gradient(100deg, transparent 38%, rgba(255, 255, 255, 0.055) 50%, transparent 63%);
}

.site-header .shell { position: relative; }
.brand-logo,
.site-footer .brand-logo { background: transparent; padding: 0; }
.site-header .desktop-links { color: #f6f2e8; }
.site-header .desktop-links > a:not(.nav-book) { opacity: 0.86; }
.site-header .desktop-links > a:not(.nav-book):hover,
.site-header .desktop-links > a:not(.nav-book):focus-visible { opacity: 1; color: #e3cea1; }
.site-header .nav-book {
  color: #f6f2e8;
  background: rgba(255, 255, 255, 0.075);
  border: 1px solid rgba(227, 206, 161, 0.62);
  box-shadow: inset 0 1px rgba(255, 255, 255, 0.08);
}
.site-header .nav-book:hover,
.site-header .nav-book:focus-visible { background: #1e4fc4; border-color: #1e4fc4; }
.site-header .menu-button { color: #e3cea1; }

@media (max-width: 720px) {
  .site-header .desktop-links {
    color: #f6f2e8;
    background:
      radial-gradient(circle at 70% 0%, rgba(46, 91, 204, 0.58), transparent 40%),
      linear-gradient(145deg, #090b12, #081735);
  }
  .site-header .nav-book { margin-top: 14px; }
}