/* ========== 原有样式保持不变 ========== */
header {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(14px);
  background: rgba(255,255,255,.92);
  border-bottom: 1px solid rgba(16,35,63,.06);
  box-shadow: 0 4px 20px rgba(24,55,110,.08);
}

.nav {
  height: 78px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.brand {
  font-size: 30px;
  font-weight: 800;
  color: #153666;
  letter-spacing: -.04em;
}

/* ========== Solutions 专属卡片样式 ========== */
.nav-item-solutions .nav-dropdown,
.nav-item-applications .nav-dropdown {
  padding: 32px 0;
}

.nav-item-applications .dropdown-grid-solutions {
  grid-template-columns: minmax(280px, 400px);
  justify-content: start;
}

.nav-item-applications .dropdown-card {
  border-right: none;
}

.dropdown-grid-solutions {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 40px;
}

/* 卡片样式 - 无边框，用竖线分割 */
.dropdown-card {
  background: #ffffff;
  padding: 24px 20px 20px;
  transition: all 0.3s ease;
  border: none;
  border-right: 1px solid #e5edf5;
}

.dropdown-card:last-child {
  border-right: none;
}

.dropdown-card:hover {
  transform: translateY(-4px);
}

/* 卡片头部容器 - 图标和标题在同一行 */
.dropdown-card-header {
  display: flex;
  align-items: center;
  gap: 14px;
}

/* 卡片图标 - 图片容器 */
.dropdown-card-icon {
  width: 48px;
  height: 48px;
  flex: 0 0 48px;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border-radius: 12px;
  transition: all 0.3s ease;
}

.dropdown-card-icon img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  transition: opacity 0.3s ease;
}

.icon-hover {
  position: absolute;
  top: 0;
  left: 0;
  opacity: 0;
}

.dropdown-card:hover .icon-default {
  opacity: 0;
}

.dropdown-card:hover .icon-hover {
  opacity: 1;
}

/* 卡片标题 */
.dropdown-card-title {
  flex: 1 1 auto;
  min-width: 0;
  font-size: 18px;
  font-weight: 700;
  color: #153666;
  margin: 0;
  letter-spacing: 0.02em;
  line-height: 1.3;
  word-break: break-word;
}

/* 卡片列表项 */
.dropdown-card-list {
  display: flex;
  flex-direction: column;
  gap: 2px;
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1px solid #e5edf5;
}

.dropdown-card .dropdown-item {
  display: flex;
  align-items: center;
  padding: 6px 8px;
  border-radius: 6px;
  transition: all 0.2s ease;
  font-size: 16px;
  color: #48637c;
  text-decoration: none;
}

.dropdown-card .dropdown-item:hover {
  background: #f0f6ff;
  color: #1f6ed8;
}

.dropdown-arrow {
  color: #1f6ed8;
  font-size: 14px;
  font-weight: 700;
  margin-right: 8px;
  opacity: 0.6;
  transition: all 0.2s ease;
}

.dropdown-card .dropdown-item:hover .dropdown-arrow {
  opacity: 1;
  transform: translateX(2px);
}

/* ========== Applications 样式 ========== */
.dropdown-column .dropdown-item {
  display: flex;
  flex-direction: column;
  padding: 10px 14px;
  border-radius: 8px;
  transition: all 0.2s ease;
  text-decoration: none;
}

.dropdown-column .dropdown-item:hover {
  background: #f0f6ff;
}

.dropdown-column .dropdown-title {
  font-size: 14px;
  font-weight: 600;
  color: #244064;
}

.dropdown-column .dropdown-desc {
  font-size: 12px;
  color: #8899aa;
  margin-top: 2px;
}

/* ========== 导航链接样式 ========== */
.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
  color: #244064;
  font-weight: 500;
}

.nav-links a {
  position: relative;
  padding: 6px 0;
  text-decoration: none;
  color: inherit;
}

.nav-links a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -2px;
  width: 0;
  height: 2px;
  border-radius: 4px;
  background: #1f6ed8;
  transition: 0.25s ease;
}

.nav-links a:hover::after {
  width: 100%;
}

.nav-links a:hover {
  color: #1f6ed8;
}

.nav-item {
  position: relative;
}

.nav-parent {
  position: relative;
}

/* ========== 下拉菜单容器 ========== */
.nav-dropdown {
  position: fixed;
  left: 0;
  right: 0;
  top: 78px;
  background: #fff;
  box-shadow: 0 8px 32px rgba(24,55,110,.12);
  padding: 24px 0;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px);
  transition: all 0.3s ease;
  z-index: 100;
  border-top: 1px solid rgba(31,110,216,.08);
}

.nav-item:hover .nav-dropdown,
.nav-dropdown:hover {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

/* ========== 通用下拉网格 ========== */
.dropdown-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 0px;
}

/* ========== 搜索框 ========== */
.nav-search {
  position: relative;
  display: flex;
  align-items: center;
}

.search-toggle {
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  color: #48637c;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: 0.2s ease;
}

.search-toggle:hover {
  color: #1f6ed8;
}

.search-box {
  position: absolute;
  right: 100%;
  top: 50%;
  transform: translateY(-50%);
  display: flex;
  align-items: center;
  background: #fff;
  border-radius: 8px;
  box-shadow: 0 4px 20px rgba(24,55,110,.15);
  padding: 4px 8px;
  opacity: 0;
  visibility: hidden;
  margin-right: 10px;
  transition: 0.3s ease;
}

.nav-search.active .search-box {
  opacity: 1;
  visibility: visible;
}

.search-box form {
  display: flex;
  align-items: center;
}

.search-box input[name="keyword"] {
  border: none;
  outline: none;
  font-size: 14px;
  width: 200px;
  padding: 8px 12px;
  background: transparent;
}

.search-submit {
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px 8px;
  color: #8899aa;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: 0.2s ease;
}

.search-submit:hover {
  color: #1f6ed8;
}

.search-close {
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px 8px;
  color: #8899aa;
  display: flex;
}

.search-close:hover {
  color: #48637c;
}

/* ========== 容器 ========== */
header .container {
  width: min(calc(100% - 40px), 1240px);
  margin: auto;
}

/* ========== 移动端汉堡菜单 ========== */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 16px;
  z-index: 101;
  position: relative;
  margin-left: auto;
  margin-right: 0;
  width: 48px;
  height: 48px;
  box-sizing: border-box;
}

.mobile-menu-toggle span {
  width: 24px;
  height: 2px;
  background: #244064;
  border-radius: 2px;
  transition: all 0.3s ease;
  position: relative;
}

.mobile-menu-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translateY(6px) translateX(6px);
}

.mobile-menu-toggle.active span:nth-child(2) {
  opacity: 0;
}

.mobile-menu-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translateY(-6px) translateX(6px);
}

.mobile-nav {
  display: none;
  position: absolute;
  top: calc(100% + 0px);
  left: 0;
  right: 0;
  background: #fff;
  box-shadow: 0 8px 32px rgba(24,55,110,.12);
  flex-direction: column;
  padding: 16px 0;
  z-index: 100;
}

.mobile-nav a {
  padding: 14px 24px;
  color: #244064;
  font-weight: 500;
  border-bottom: 1px solid rgba(23,64,124,.06);
  text-decoration: none;
}

.mobile-nav a:last-child {
  border-bottom: none;
}

.mobile-nav.active {
  display: flex;
}

/* ========== 响应式 ========== */
@media (max-width: 1024px) {
  .dropdown-grid-solutions {
    grid-template-columns: repeat(2, 1fr);
  }
  .dropdown-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .dropdown-card:nth-child(2n) {
    border-right: none;
  }
  .dropdown-card:nth-child(2n+1) {
    border-right: 1px solid #e5edf5;
  }
  .dropdown-card:nth-last-child(-n+2) {
    border-bottom: none;
  }
}

@media (max-width: 768px) {
  .nav { height: 70px; }
  .nav-links { display: none; }
  .mobile-menu-toggle { display: flex; }
  .mobile-nav { display: none; }
  .mobile-nav.active { display: flex; }
  header .container {
    width: min(calc(100% - 28px), 1240px);
  }
  .dropdown-grid-solutions {
    grid-template-columns: 1fr;
    padding: 0 20px;
  }
  .dropdown-grid {
    grid-template-columns: 1fr;
    padding: 0 20px;
  }
  .dropdown-card {
    border-right: none !important;
    border-bottom: 1px solid #e5edf5;
  }
  .dropdown-card:last-child {
    border-bottom: none;
  }
}