.site-header {
  position: sticky;
  top: 0;
  z-index: 80;
  background: var(--bg-page);
  border-bottom: 1px solid var(--border-light);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  text-decoration: none;
  min-width: 0;
}

.brand-avatar {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  object-fit: cover;
  border: 1px solid var(--border-light);
  flex-shrink: 0;
}

.brand-title {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--brand-ink);
  letter-spacing: -0.02em;
  line-height: 1;
}

.brand-sub {
  font-size: 0.7rem;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.nav-menu {
  display: flex;
  gap: 1.25rem;
}

.nav-item {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.92rem;
  font-weight: 500;
  padding: 0.25rem 0.5rem;
  border-radius: var(--radius);
  transition: all 0.15s ease;
}

.nav-item:hover {
  color: var(--brand-ink);
  background: var(--bg-hover);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.btn-icon {
  background: transparent;
  border: 1px solid var(--border-light);
  color: var(--text-main);
  border-radius: var(--radius);
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  flex-shrink: 0;
}

.btn-icon:hover {
  background: var(--bg-hover);
}

/* Theme Icon Visibility */
[data-theme="light"] .sun-icon { display: none; }
[data-theme="dark"] .moon-icon { display: none; }

/* Hamburger Icon */
.mobile-only { display: none; }
.desktop-only { display: flex; }

.hamburger-line {
  display: block;
  width: 18px;
  height: 2px;
  background: var(--brand-ink);
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.hamburger-line + .hamburger-line {
  margin-top: 5px;
}

/* Mobile Dropdown Panel */
.mobile-nav-panel {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-light);
  box-shadow: var(--shadow-md);
  padding: 1.25rem;
  flex-direction: column;
  gap: 1rem;
}

.mobile-nav-panel.is-active {
  display: flex;
  animation: slideDown 0.2s ease forwards;
}

@keyframes slideDown {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: translateY(0); }
}

.mobile-nav-links {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.mobile-nav-item {
  color: var(--text-main);
  font-size: 1.05rem;
  font-weight: 500;
  text-decoration: none;
  padding: 0.65rem 0.75rem;
  border-radius: var(--radius);
  transition: background 0.15s ease;
}

.mobile-nav-item:hover {
  background: var(--bg-hover);
}

/* Responsive Rules for Small Devices (Phones & Small Tablets) */
@media (max-width: 820px) {
  .desktop-only { display: none !important; }
  .desktop-cta { display: none !important; }
  .mobile-only { display: flex !important; }

  /* Animated Hamburger to X */
  #mobileMenuToggle[aria-expanded="true"] .hamburger-line:first-child {
    transform: translateY(3.5px) rotate(45deg);
  }
  #mobileMenuToggle[aria-expanded="true"] .hamburger-line:last-child {
    transform: translateY(-3.5px) rotate(-45deg);
  }
}