/* ============================================
   Header - Navigation and Logo
   ============================================ */

/* ========== Header Base ========== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background-color: transparent;
  /* z-index higher than nav-mobile so hamburger button is always clickable */
  z-index: calc(var(--z-header) + 1);
  transition:
    background-color var(--transition-base),
    height var(--transition-base),
    box-shadow var(--transition-base);
}

/* Scrolled state */
.header.scrolled {
  height: var(--header-height-scrolled);
  background-color: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  box-shadow: var(--shadow-md);
}

/* Dark header variant (for light backgrounds) */
.header.header-dark {
  background-color: var(--gray-900);
}

.header.header-dark.scrolled {
  background-color: rgba(26, 26, 26, 0.95);
}

/* ========== Header Inner ========== */
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--container-xl);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

/* ========== Logo ========== */
.logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  text-decoration: none;
  flex-shrink: 0;
}

.logo-img {
  height: 44px;
  width: auto;
  transition: height var(--transition-base);
}

.header.scrolled .logo-img {
  height: 36px;
}

.logo-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.logo-cn {
  font-size: var(--text-sm);
  font-weight: var(--font-bold);
  color: var(--white);
  transition: color var(--transition-base);
}

.header.scrolled .logo-cn {
  color: var(--gray-900);
}

.logo-en {
  font-size: var(--text-xs);
  color: rgba(255, 255, 255, 0.7);
  transition: color var(--transition-base);
}

.header.scrolled .logo-en {
  color: var(--gray-500);
}

/* Hide text on mobile */
@media (max-width: 767px) {
  .logo-text {
    display: none;
  }
}

/* ========== Desktop Navigation ========== */
.nav-desktop {
  display: none;
}

@media (min-width: 1024px) {
  .nav-desktop {
    display: block;
  }
}

.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-8);
}

.nav-link {
  position: relative;
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  color: rgba(255, 255, 255, 0.9);
  padding: var(--space-2) 0;
  transition: color var(--transition-fast);
}

.header.scrolled .nav-link {
  color: var(--gray-700);
}

.nav-link:hover {
  color: var(--white);
}

.header.scrolled .nav-link:hover {
  color: var(--primary);
}

/* Active state */
.nav-link.active {
  color: var(--white);
}

.header.scrolled .nav-link.active {
  color: var(--primary);
}

/* Underline effect */
.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--primary);
  transition: width var(--transition-base);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

/* ========== Header Actions ========== */
.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

/* Language Dropdown */
.lang-dropdown {
  position: relative;
}

.lang-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  min-width: 80px;
  height: 36px;
  padding: 0 var(--space-3);
  font-size: var(--text-sm);
  font-weight: var(--font-semibold);
  color: var(--white);
  background-color: rgba(255, 255, 255, 0.15);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.header.scrolled .lang-toggle {
  color: var(--gray-700);
  background-color: var(--gray-100);
  border-color: var(--gray-200);
}

.lang-toggle:hover {
  background-color: rgba(255, 255, 255, 0.25);
  border-color: rgba(255, 255, 255, 0.4);
}

.header.scrolled .lang-toggle:hover {
  background-color: var(--gray-200);
  border-color: var(--gray-300);
}

.lang-arrow {
  transition: transform var(--transition-fast);
}

.lang-dropdown.open .lang-arrow {
  transform: rotate(180deg);
}

/* Language Dropdown Menu */
.lang-menu {
  position: absolute;
  top: calc(100% + var(--space-2));
  right: 0;
  min-width: 120px;
  padding: var(--space-2) 0;
  background-color: var(--white);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-10px);
  transition: all var(--transition-fast);
  z-index: 100;
}

.lang-dropdown.open .lang-menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.lang-option {
  display: flex;
  align-items: center;
  width: 100%;
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  color: var(--gray-700);
  background: transparent;
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-align: left;
}

.lang-option:hover {
  background-color: var(--gray-100);
  color: var(--primary);
}

.lang-option.active {
  color: var(--primary);
  background-color: var(--primary-alpha-10);
}

/* ========== Mobile Menu Toggle ========== */
.menu-toggle {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 44px;
  height: 44px;
  padding: 0;
  background: transparent;
  border: none;
  cursor: pointer;
  z-index: calc(var(--z-header) + 10);
}

@media (min-width: 1024px) {
  .menu-toggle {
    display: none;
  }
}

.hamburger {
  position: relative;
  width: 24px;
  height: 2px;
  background-color: var(--white);
  border-radius: 2px;
  transition: background-color var(--transition-fast);
}

.header.scrolled .hamburger {
  background-color: var(--gray-900);
}

.hamburger::before,
.hamburger::after {
  content: '';
  position: absolute;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: inherit;
  border-radius: 2px;
  transition: transform var(--transition-base);
}

.hamburger::before {
  top: -7px;
}

.hamburger::after {
  bottom: -7px;
}

/* Menu open state */
.menu-toggle.active .hamburger {
  background-color: transparent;
}

.menu-toggle.active .hamburger::before {
  transform: translateY(7px) rotate(45deg);
  background-color: var(--gray-900);
}

.menu-toggle.active .hamburger::after {
  transform: translateY(-7px) rotate(-45deg);
  background-color: var(--gray-900);
}

/* ========== Mobile Navigation ========== */
.nav-mobile {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  /* Subtle dark overlay - mostly transparent */
  background: linear-gradient(to bottom,
      rgba(0, 0, 0, 0.3) 0%,
      rgba(0, 0, 0, 0.15) 50%,
      rgba(0, 0, 0, 0.05) 100%);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  /* z-index same as header - now works because nav-mobile is outside header */
  z-index: var(--z-header);
  display: flex;
  flex-direction: column;
  align-items: stretch;
  justify-content: flex-start;
  padding: calc(var(--header-height) + var(--space-4)) var(--container-padding) var(--space-8);
  /* Ensure menu content is scrollable and always visible */
  overflow-y: auto;
  overflow-x: hidden;
  -webkit-overflow-scrolling: touch;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-20px);
  transition:
    opacity var(--transition-base),
    visibility var(--transition-base),
    transform var(--transition-base);
}

.nav-mobile.active {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

/* Frosted glass card for nav items only */
.nav-mobile .nav-list {
  flex-direction: column;
  align-items: stretch;
  gap: 0;
  /* Glassmorphism on the list container */
  background: rgba(255, 255, 255, 0.75);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-radius: var(--radius-xl);
  border: 1px solid rgba(255, 255, 255, 0.4);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
  padding: var(--space-2);
  overflow: hidden;
}

.nav-mobile .nav-link {
  display: block;
  width: 100%;
  padding: var(--space-4) var(--space-4);
  font-size: var(--text-lg);
  font-weight: var(--font-semibold);
  color: var(--gray-900);
  border-radius: var(--radius-lg);
  transition: background-color var(--transition-fast);
}

.nav-mobile .nav-link:hover,
.nav-mobile .nav-link.active {
  color: var(--primary);
  background-color: rgba(227, 27, 35, 0.08);
}

.nav-mobile .nav-link::after {
  display: none;
}

/* Mobile nav contact info - also with frosted glass */
.nav-mobile-contact {
  margin-top: var(--space-4);
  padding: var(--space-4);
  background: rgba(255, 255, 255, 0.65);
  backdrop-filter: blur(16px) saturate(150%);
  -webkit-backdrop-filter: blur(16px) saturate(150%);
  border-radius: var(--radius-xl);
  border: 1px solid rgba(255, 255, 255, 0.3);
}

.nav-mobile-contact p {
  font-size: var(--text-sm);
  color: var(--gray-700);
  margin-bottom: var(--space-2);
}

.nav-mobile-contact a {
  color: var(--primary);
  font-weight: var(--font-medium);
}

/* ========== Body scroll lock ========== */
body.menu-open {
  overflow: hidden;
}

/* ========== CTA Button in Header (optional) ========== */
.header-cta {
  display: none;
}

@media (min-width: 1024px) {
  .header-cta {
    display: inline-flex;
    margin-left: var(--space-4);
  }
}