/* ============================================================
 * 布局 —— 公共头部 / 导航 / 页脚 / 栅格
 * 头部与页脚由 nav.js 统一注入，class 名与 JS 模板保持一致
 * ============================================================ */

/* ===================== 头部 ===================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  background: var(--color-bg);
  box-shadow: var(--shadow-sm);
}

/* ---- 上排：Logo + 搜索 ---- */
.site-header__top-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  padding: 12px 0;
}

/* ---- 下排：导航条 ---- */
.site-header__bar {
  display: none; /* 移动端隐藏，导航由汉堡菜单接管 */
  background: var(--color-bg);
  border-top: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

/* ---- Logo ---- */
.site-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.site-logo__img {
  height: 40px;
  width: auto;
  display: block;
  flex-shrink: 0;
  background: var(--color-primary);
  padding: 6px 12px;
  border-radius: var(--radius-md);
}

/* ---- 站内搜索 ---- */
.site-search-wrap {
  flex: 1 1 260px;
  max-width: 380px;
  margin-left: var(--space-lg);
}

.site-search {
  display: flex;
  align-items: center;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  overflow: hidden;
  background: var(--color-bg);
}

.site-search__hot {
  display: none; /* 移动端隐藏，避免顶部拥挤 */
  align-items: center;
  flex-wrap: wrap;
  gap: 4px 10px;
  margin-top: 6px;
  padding: 0 4px;
  font-size: var(--fs-xs);
  color: var(--color-text-muted);
}

.site-search__hot-label {
  color: var(--color-text-muted);
}

.site-search__hot-item {
  color: var(--color-text-secondary);
}

.site-search__hot-item:hover {
  color: var(--color-primary);
}

.site-search__input {
  flex: 1;
  min-width: 0;
  border: none;
  outline: none;
  padding: 9px 16px;
  font-size: var(--fs-sm);
  background: transparent;
  color: var(--color-text);
}

.site-search__btn {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  align-self: stretch;
  background: var(--color-primary);
  color: #fff;
  transition: background var(--transition-fast);
}

.site-search__btn:hover {
  background: var(--color-primary-dark);
}

.site-search__btn svg {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

.site-logo__icon {
  width: 38px;
  height: 38px;
  flex-shrink: 0;
}

.site-logo__text {
  display: flex;
  flex-direction: column;
  line-height: 1.25;
}

.site-logo__name {
  font-size: 17px;
  font-weight: 700;
  color: var(--color-heading);
  white-space: nowrap;
}

.site-logo__sub {
  font-size: 11px;
  color: var(--color-text-muted);
  letter-spacing: 0.5px;
  white-space: nowrap;
}

/* ---- 桌面导航 ---- */
.site-nav {
  display: none; /* 移动端默认隐藏，由汉堡菜单接管 */
}

.site-nav__list {
  display: flex;
  align-items: center;
}

.site-nav__item {
  position: relative;
}

.site-nav__link {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 0 18px;
  height: 48px;
  line-height: 48px;
  color: var(--color-heading);
  font-size: 15px;
  font-weight: 500;
  white-space: nowrap;
  transition: background var(--transition-fast), color var(--transition-fast);
}

.site-nav__link:hover,
.site-nav__item.is-active > .site-nav__link {
  color: #fff;
  background: var(--color-primary);
}

.site-nav__caret {
  width: 8px;
  height: 8px;
  border-right: 1.5px solid currentColor;
  border-bottom: 1.5px solid currentColor;
  transform: rotate(45deg) translateY(-2px);
  transition: transform var(--transition-fast);
}

/* 下拉菜单 */
.site-nav__dropdown {
  position: absolute;
  top: 100%;
  left: 0;
  min-width: 160px;
  background: var(--color-bg);
  box-shadow: var(--shadow-md);
  border-radius: 0 0 var(--radius-md) var(--radius-md);
  padding: var(--space-sm) 0;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity var(--transition-fast), transform var(--transition-fast),
    visibility var(--transition-fast);
  z-index: var(--z-dropdown);
}

.site-nav__item:hover > .site-nav__dropdown,
.site-nav__item:focus-within > .site-nav__dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.site-nav__dropdown a {
  display: block;
  padding: 10px 20px;
  font-size: 14px;
  color: var(--color-text);
  white-space: nowrap;
}

.site-nav__dropdown a:hover,
.site-nav__dropdown a.is-active {
  color: var(--color-primary);
  background: var(--color-primary-bg);
}

/* ---- 汉堡按钮（移动端） ---- */
.nav-toggle {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  padding: 8px;
  border-radius: var(--radius-sm);
}

.nav-toggle__bar {
  display: block;
  height: 2px;
  width: 100%;
  background: var(--color-heading);
  border-radius: 2px;
  transition: transform var(--transition-normal), opacity var(--transition-fast);
}

body.menu-open .nav-toggle__bar:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

body.menu-open .nav-toggle__bar:nth-child(2) {
  opacity: 0;
}

body.menu-open .nav-toggle__bar:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ---- 移动端全屏菜单 ---- */
.mobile-menu {
  position: fixed;
  inset: 76px 0 0 0;
  background: var(--color-bg);
  z-index: var(--z-mobile-menu);
  overflow-y: auto;
  padding: var(--space-md);
  transform: translateX(100%);
  transition: transform var(--transition-normal);
  visibility: hidden;
}

body.menu-open .mobile-menu {
  transform: translateX(0);
  visibility: visible;
}

body.menu-open {
  overflow: hidden;
}

.mobile-menu__link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: 14px var(--space-sm);
  font-size: var(--fs-md);
  font-weight: 500;
  color: var(--color-text);
  border-bottom: 1px solid var(--color-border);
  text-align: left;
}

.mobile-menu__link.is-active {
  color: var(--color-primary);
}

.mobile-menu__group .mobile-menu__link::after {
  content: "";
  width: 8px;
  height: 8px;
  border-right: 1.5px solid currentColor;
  border-bottom: 1.5px solid currentColor;
  transform: rotate(45deg);
  transition: transform var(--transition-fast);
}

.mobile-menu__group.is-open > .mobile-menu__link::after {
  transform: rotate(-135deg);
}

.mobile-menu__sub {
  display: none;
  background: var(--color-bg-gray);
  border-radius: var(--radius-md);
  margin: var(--space-sm) 0;
}

.mobile-menu__group.is-open > .mobile-menu__sub {
  display: block;
}

.mobile-menu__sub a {
  display: block;
  padding: 12px var(--space-lg);
  font-size: 15px;
  color: var(--color-text-secondary);
}

.mobile-menu__sub a.is-active {
  color: var(--color-primary);
  font-weight: 500;
}

/* ===================== 页脚 ===================== */
.site-footer {
  background: var(--color-bg-dark);
  color: rgba(255, 255, 255, 0.75);
  font-size: var(--fs-sm);
}

.site-footer__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-xl);
  padding: var(--space-xl) 0;
}

.site-footer__title {
  color: #fff;
  font-size: var(--fs-md);
  margin-bottom: var(--space-md);
}

.site-footer__about {
  line-height: 1.9;
}

.site-footer__logo {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: var(--space-md);
}

.site-footer__logo-img {
  height: 48px;
  width: auto;
  display: block;
  background: var(--color-primary);
  padding: 8px 12px;
  border-radius: var(--radius-md);
}

.site-footer__logo .site-logo__name {
  color: #fff;
}

.site-footer__links li {
  margin-bottom: 10px;
}

.site-footer__links a {
  color: rgba(255, 255, 255, 0.75);
}

.site-footer__links a:hover {
  color: #fff;
}

.site-footer__contact li {
  display: flex;
  gap: var(--space-sm);
  margin-bottom: 10px;
  line-height: 1.6;
}

.site-footer__contact .icon {
  flex-shrink: 0;
  width: 16px;
  height: 16px;
  margin-top: 4px;
  fill: var(--color-accent);
}

.site-footer__bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  padding: var(--space-md) 0;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm) var(--space-lg);
  justify-content: space-between;
  font-size: var(--fs-xs);
  color: rgba(255, 255, 255, 0.5);
}

/* ===================== 栅格 ===================== */
.grid {
  display: grid;
  gap: var(--space-lg);
}

/* 栅格子项默认最小宽度为 0，避免 nowrap 内容撑破列宽导致整行溢出 */
.grid > * {
  min-width: 0;
}

/* ===================== 响应式 ===================== */

/* 平板端 ≥768px */
@media (min-width: 768px) {
  .site-logo__img {
    height: 56px;
    padding: 8px 18px;
  }

  .site-search__hot {
    display: flex;
  }

  .mobile-menu {
    inset: 108px 0 0 0;
  }

  .site-footer__grid {
    grid-template-columns: 1.4fr 1fr 1.4fr;
  }

  .grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

/* 桌面端 ≥1024px */
@media (min-width: 1024px) {
  .site-header__bar {
    display: block;
  }

  .site-nav {
    display: block;
  }

  .nav-toggle,
  .mobile-menu {
    display: none;
  }

  .site-footer__grid {
    grid-template-columns: 1.6fr 1fr 1fr 1.2fr;
    gap: var(--space-2xl);
  }

  .grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}