/* ========================================
   header.css — 顶部导航栏
   作用：
   1. 固定在页面顶部，初始透明（适配全屏 Hero 背景）
   2. 滚动后变为白底 + 阴影（通过 .scrolled 类切换）
   3. 桌面端：水平导航 + 二级下拉菜单（hover 展开）
   4. 移动端（<992px）：汉堡菜单 + 侧滑面板 + 手风琴下拉
   5. 语言切换下拉菜单（7 种语言）
   ======================================== */

/* ===== 导航栏主体 =====
   固定定位在顶部，初始背景透明（在 Hero 图片上方时不遮挡）
   通过 .scrolled 类在 JS 中切换为白底 */
#site-header {
  position: fixed;
  left: 0;
  right: 0;
  top: 0;
  z-index: 1000;
  height: var(--header-height);
  display: flex;
  align-items: center;
  background-color: transparent;
  transition: background-color var(--transition-base), box-shadow var(--transition-base);
}

#site-header.scrolled {
  background-color: var(--color-bg);
  box-shadow: var(--shadow-sm);
}

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  direction: ltr;
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--space-md);
}

/* ===== Logo ===== */
.logo a {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  color: #fff;
  transition: color var(--transition-base);
}

#site-header.scrolled .logo a {
  color: var(--color-text);
}

/* ===== 导航布局 ===== */
.nav {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

.nav__menu {
  display: none;
  align-items: center;
  gap: var(--space-lg);
}

.nav__link {
  font-family: var(--font-body);
  font-size: 0.9375rem;
  font-weight: 500;
  color: #fff;
  transition: color var(--transition-base);
  position: relative;
  padding-block: var(--space-sm);
}

#site-header.scrolled .nav__link {
  color: var(--color-text);
}

.nav__link:hover,
.nav__link--active {
  color: var(--color-primary);
}

/* ===== 二级下拉菜单（Industries）===== */
.nav__dropdown {
  position: relative;
}

.dropdown__trigger {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
}

.dropdown__trigger .icon--arrow-down {
  width: 10px;
  height: 10px;
  transition: transform var(--transition-base);
}

.nav__dropdown:hover .dropdown__trigger .icon--arrow-down {
  transform: rotate(180deg);
}

.dropdown__menu {
  position: absolute;
  top: 100%;
  left: 0;
  min-width: 240px;
  background-color: var(--color-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  padding: var(--space-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity var(--transition-fast), transform var(--transition-fast), visibility var(--transition-fast);
}

.nav__dropdown:hover .dropdown__menu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.dropdown__item {
  display: block;
  padding: var(--space-sm) var(--space-md);
  font-size: 0.9375rem;
  color: var(--color-text);
  border-radius: var(--radius);
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.dropdown__item:hover {
  background-color: var(--color-primary-light);
  color: var(--color-primary);
}

/* ===== 语言切换下拉 ===== */
.lang-switch {
  display: none;
  position: relative;
  align-items: center;
  font-size: 0.8125rem;
  font-weight: 500;
  color: #fff;
}

#site-header.scrolled .lang-switch {
  color: var(--color-text);
}

.lang-switch__trigger {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-family: var(--font-body);
  font-size: 0.8125rem;
  font-weight: 500;
  color: inherit;
  cursor: pointer;
  background: none;
  border: 1px solid rgba(255, 255, 255, 0.3);
  border-radius: var(--radius);
  padding: 0.375rem 0.75rem;
  transition: color var(--transition-base), border-color var(--transition-base);
}

#site-header.scrolled .lang-switch__trigger {
  border-color: var(--color-border);
}

.lang-switch__trigger:hover {
  color: var(--color-primary);
  border-color: var(--color-primary);
}

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

.lang-switch.open .lang-switch__arrow {
  transform: rotate(180deg);
}

.lang-switch__dropdown {
  position: absolute;
  top: calc(100% + 6px);
  right: 0;
  min-width: 160px;
  background-color: var(--color-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  padding: var(--space-xs) 0;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity var(--transition-fast), transform var(--transition-fast), visibility var(--transition-fast);
  list-style: none;
  z-index: 100;
}

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

.lang-switch__option {
  display: block;
  width: 100%;
  text-align: left;
  padding: var(--space-sm) var(--space-md);
  font-family: var(--font-body);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-text);
  background: none;
  border: none;
  cursor: pointer;
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.lang-switch__option:hover {
  background-color: var(--color-primary-light);
  color: var(--color-primary);
}

.lang-switch__option--active {
  color: var(--color-primary);
  font-weight: 700;
}

/* ===== 汉堡菜单按钮（仅移动端）===== */
.mobile-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  color: #fff;
  transition: color var(--transition-base);
}

#site-header.scrolled .mobile-toggle {
  color: var(--color-text);
}

.mobile-toggle svg {
  width: 24px;
  height: 24px;
}

/* 汉堡动画 — 三条线变X */
.hamburger-line {
  transition: transform 0.3s ease, opacity 0.3s ease;
  transform-origin: center;
}

.nav__menu.open ~ .mobile-toggle .hamburger-line.top,
.mobile-toggle[aria-expanded="true"] .hamburger-line.top {
  transform: translateY(6px) rotate(45deg);
}

.nav__menu.open ~ .mobile-toggle .hamburger-line.mid,
.mobile-toggle[aria-expanded="true"] .hamburger-line.mid {
  opacity: 0;
}

.nav__menu.open ~ .mobile-toggle .hamburger-line.bot,
.mobile-toggle[aria-expanded="true"] .hamburger-line.bot {
  transform: translateY(-6px) rotate(-45deg);
}

/* ===== 桌面端（≥992px）===== */
@media (min-width: 992px) {
  .nav__menu {
    display: flex;
  }

  .lang-switch {
    display: flex;
  }

  .mobile-toggle {
    display: none;
  }
}

/* ===== 移动端（<992px）===== */
@media (max-width: 991px) {
  /* 导航容器 — 语言切换 + 汉堡右对齐 */
  .nav {
    gap: var(--space-sm);
  }

  /* 语言切换 — 始终显示在移动端，汉堡左边 */
  .lang-switch {
    display: flex;
  }

  .lang-switch__trigger {
    border-color: rgba(255, 255, 255, 0.3);
    color: #fff;
    font-size: 0.75rem;
    padding: 0.3rem 0.5rem;
  }

  #site-header.scrolled .lang-switch__trigger {
    border-color: var(--color-border);
    color: var(--color-text);
  }

  /* 汉堡按钮始终显示 */
  .mobile-toggle {
    display: flex;
  }

  /* 导航菜单 — 从右侧滑入的全屏覆盖 */
  .nav__menu {
    display: flex;
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    flex-direction: column;
    align-items: flex-start;
    background-color: var(--color-bg);
    padding: var(--space-lg) var(--space-md);
    gap: 0;
    overflow-y: auto;
    transform: translateX(100%);
    transition: transform 0.3s ease;
    z-index: 999;
  }

  .nav__menu.open {
    transform: translateX(0);
  }

  .nav__link {
    color: var(--color-text);
    display: block;
    width: 100%;
    padding: var(--space-md);
    border-bottom: 1px solid var(--color-border);
    font-size: 1rem;
  }

  .dropdown__menu {
    position: static;
    opacity: 1;
    visibility: visible;
    transform: none;
    box-shadow: none;
    padding: 0;
    min-width: auto;
    display: none;
  }

  .nav__dropdown.open .dropdown__menu {
    display: block;
  }

  .dropdown__item {
    padding: var(--space-sm) var(--space-lg);
  }

  .lang-switch__dropdown {
    position: absolute;
    right: 0;
    top: calc(100% + 4px);
  }

  .lang-switch.open .lang-switch__dropdown {
    display: block;
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
  }
}