/* --------------------------------------------------------------------------
   3. 頂部融合式導航欄 (Seamless Blended Header - Spacious & Elegant)
   -------------------------------------------------------------------------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  padding: 20px 0;
  min-height: var(--header-height);
  background: transparent;
  border-bottom: 1px solid transparent;
  z-index: 1000;
  display: flex;
  align-items: center;
  transition: var(--transition-normal);
}

.site-header.scrolled {
  padding: 12px 0;
  min-height: 72px;
  background: var(--bg-glass);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  border-bottom-color: var(--border-subtle);
  box-shadow: var(--shadow-sm);
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.site-brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand-logo {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 2px solid var(--primary-gold);
  object-fit: cover;
  box-shadow: 0 0 14px var(--primary-gold-glow);
}

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

.brand-name {
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--text-primary);
  letter-spacing: 0.3px;
  line-height: 1.2;
}

.brand-sub {
  font-size: 0.76rem;
  color: var(--primary-gold-dark);
  font-weight: 700;
  letter-spacing: 0.2px;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
}

.nav-link {
  display: inline-block;
  padding: 7px 13px;
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--text-secondary);
  border-radius: var(--radius-full);
  white-space: nowrap;
  transition: var(--transition-fast);
}

.nav-link:hover {
  color: var(--text-primary);
  background: rgba(24, 21, 19, 0.06);
}

.nav-link.active {
  color: var(--primary-gold-dark);
  background: var(--primary-gold-subtle);
  font-weight: 800;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}

.btn-header-cta {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 9px 22px;
  background: linear-gradient(135deg, var(--primary-gold) 0%, var(--primary-gold-dark) 100%);
  color: #ffffff;
  font-size: 0.9rem;
  font-weight: 800;
  border-radius: var(--radius-full);
  box-shadow: 0 4px 16px var(--primary-gold-glow);
  white-space: nowrap;
  transition: var(--transition-fast);
}

.btn-header-cta:hover {
  background: linear-gradient(135deg, var(--primary-gold-light) 0%, var(--primary-gold) 100%);
  transform: translateY(-1px);
  box-shadow: 0 6px 22px var(--primary-gold-glow);
}

.mobile-nav-toggle,
.mobile-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  padding: 8px;
  background: #ffffff;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  cursor: pointer;
  flex-shrink: 0;
}

.mobile-nav-toggle span,
.mobile-toggle span {
  display: block;
  height: 2.5px;
  width: 100%;
  background: var(--text-primary);
  transition: var(--transition-fast);
  border-radius: 2px;
}

@media (max-width: 768px) {
  .nav-menu {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: rgba(250, 248, 244, 0.98);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    flex-direction: column;
    padding: 20px 24px;
    gap: 10px;
    border-bottom: 1px solid var(--border-light);
    transform: translateY(-150%);
    opacity: 0;
    pointer-events: none;
    transition: var(--transition-normal);
  }

  .nav-menu.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
    box-shadow: var(--shadow-md);
  }

  .nav-link {
    width: 100%;
    text-align: center;
    padding: 12px 16px;
    font-size: 1rem;
  }

  .mobile-nav-toggle,
  .mobile-toggle {
    display: flex;
  }

  .btn-header-cta {
    display: none;
  }
}