/* ============================================
   YUGM AI - Header / Navigation
   ============================================ */

.site-header {
  position: fixed;
  inset: 0 0 auto;
  height: var(--header-height);
  z-index: var(--z-sticky);
  background: rgba(5, 12, 21, 0.62);
  border-bottom: 1px solid transparent;
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  transition: background-color var(--transition-base), border-color var(--transition-base), box-shadow var(--transition-base), transform var(--transition-base);
}

.site-header.scrolled {
  background: rgba(5, 12, 21, 0.9);
  border-bottom-color: rgba(178, 191, 212, 0.14);
  box-shadow: 0 16px 36px rgba(2, 6, 13, 0.28);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-5);
  width: 100%;
  max-width: var(--max-width);
  height: 100%;
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.header-logo {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
  flex-shrink: 0;
}

.header-logo img {
  width: auto;
  height: 48px;
  object-fit: contain;
  filter: drop-shadow(0 10px 24px rgba(32, 131, 255, 0.18));
}

.header-logo-text {
  font-family: var(--font-display);
  font-size: 1.32rem;
  font-weight: var(--font-extrabold);
  color: var(--color-text-white);
  letter-spacing: -0.03em;
}

.header-nav {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  padding: 0.35rem;
  border-radius: var(--radius-full);
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid rgba(178, 191, 212, 0.08);
}

.nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  min-height: 40px;
  padding: 0.7rem 1rem;
  border-radius: var(--radius-full);
  color: var(--color-text-white-secondary);
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-text-white);
  background: rgba(255, 255, 255, 0.06);
}

.nav-link.active {
  box-shadow: inset 0 0 0 1px rgba(127, 182, 255, 0.16);
}

.nav-dropdown {
  position: relative;
}

.nav-dropdown-trigger svg {
  width: 14px;
  height: 14px;
  transition: transform var(--transition-fast);
}

.nav-dropdown:hover .nav-dropdown-trigger svg,
.nav-dropdown:focus-within .nav-dropdown-trigger svg {
  transform: rotate(180deg);
}

.nav-dropdown-menu {
  position: absolute;
  top: calc(100% + 12px);
  left: 50%;
  min-width: 250px;
  padding: var(--space-2);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border-dark);
  background: rgba(9, 18, 31, 0.96);
  box-shadow: var(--shadow-xl);
  transform: translateX(-50%) translateY(10px);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition-fast), transform var(--transition-fast), visibility var(--transition-fast);
}

.nav-dropdown:hover .nav-dropdown-menu,
.nav-dropdown:focus-within .nav-dropdown-menu {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}

.nav-dropdown-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-3);
  padding: 0.9rem 1rem;
  border-radius: var(--radius-md);
  color: var(--color-text-white-secondary);
  font-size: var(--text-sm);
  line-height: 1.45;
}

.nav-dropdown-item:hover {
  color: var(--color-text-white);
  background: rgba(255, 255, 255, 0.05);
}

.nav-dropdown-item svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  color: var(--color-accent-soft);
  margin-top: 1px;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  flex-shrink: 0;
}

.hamburger {
  display: none;
  position: relative;
  width: 44px;
  height: 44px;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  border-radius: var(--radius-full);
  border: 1px solid rgba(178, 191, 212, 0.14);
  background: rgba(255, 255, 255, 0.03);
}

.hamburger span {
  width: 18px;
  height: 2px;
  border-radius: var(--radius-full);
  background: var(--color-text-white);
  transition: transform var(--transition-base), opacity var(--transition-base);
  transform-origin: center;
}

.hamburger.active span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.hamburger.active span:nth-child(2) {
  opacity: 0;
}

.hamburger.active span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.mobile-menu {
  display: none;
  position: fixed;
  inset: var(--header-height) 0 0;
  z-index: var(--z-modal);
  padding: var(--space-8) var(--space-4) var(--space-10);
  background:
    linear-gradient(180deg, rgba(4, 9, 16, 0.98), rgba(4, 9, 16, 0.99)),
    radial-gradient(circle at top right, rgba(32, 131, 255, 0.14), transparent 32%);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  overflow-y: auto;
  transition: opacity var(--transition-base), visibility var(--transition-base);
}

.mobile-menu.active {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}

.mobile-menu .nav-link {
  width: 100%;
  justify-content: space-between;
  min-height: 54px;
  margin-bottom: var(--space-2);
  padding: 0.95rem 1rem;
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid rgba(178, 191, 212, 0.08);
  font-size: var(--text-base);
}

.mobile-menu .header-actions {
  margin-top: var(--space-6);
  flex-direction: column;
  align-items: stretch;
}

.mobile-menu .header-actions .btn {
  width: 100%;
  justify-content: center;
}

@media (max-width: 1180px) {
  .header-nav {
    gap: 0;
  }

  .nav-link {
    padding-inline: 0.85rem;
  }
}

@media (max-width: 1024px) {
  .header-nav,
  .site-header .header-actions {
    display: none;
  }

  .hamburger,
  .mobile-menu {
    display: flex;
  }

  .mobile-menu {
    flex-direction: column;
  }
}

@media (max-width: 768px) {
  .header-inner {
    padding: 0 var(--space-4);
  }

  .header-logo img {
    height: 44px;
  }

  .header-logo-text {
    font-size: 1.12rem;
  }
}