/* ============================================
   导航栏 & 页脚 - 深色科技氛围
   ============================================ */

/* ========== 导航栏 ========== */
.header {
  position: sticky;
  top: 0;
  z-index: 999;
  background: linear-gradient(120deg, rgba(3, 8, 20, 0.98), rgba(9, 22, 45, 0.94));
  backdrop-filter: blur(18px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.55);
}

.header .container {
  max-width: none;
  width: 100%;
  padding-left: clamp(1.5rem, 7vw, 8rem);
  padding-right: clamp(1.5rem, 7vw, 8rem);
}

.navbar {
  padding: 14px 0;
}

.navbar-wrapper {
  display: grid;
  grid-template-columns: auto 1fr;
  align-items: center;
  gap: var(--spacing-lg);
}

.logo-link {
  display: flex;
  align-items: center;
  color: #fff;
  text-transform: none;
  letter-spacing: 0.04em;
  font-weight: var(--font-weight-semibold);
}

.logo-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
  gap: 2px;
  max-width: 420px;
}

.logo-title {
  font-size: 17px;
  font-weight: var(--font-weight-bold);
}

.logo-subtitle {
  font-size: 11px;
  letter-spacing: 0.32em;
  color: var(--color-text-muted);
  text-transform: uppercase;
}

.navbar-menu {
  display: flex;
  flex-wrap: nowrap;
  justify-content: center;
  align-items: center;
  width: 100%;
  list-style: none;
  margin: 0;
  padding: 8px 12px;
  gap: 6px;
  border-radius: var(--radius-full);
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid rgba(255, 255, 255, 0.08);
  box-shadow: inset 0 1px 1px rgba(255, 255, 255, 0.04);
  backdrop-filter: blur(12px);
}

.nav-item {
  position: relative;
  flex: 0 0 auto;
}

.nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: 10px 16px;
  color: rgba(255, 255, 255, 0.7);
  font-weight: var(--font-weight-medium);
  border-radius: var(--radius-full);
  border: none;
  transition: color var(--transition-fast), background var(--transition-fast), transform var(--transition-fast);
  white-space: nowrap;
}

.nav-link::before {
  content: '';
  position: absolute;
  left: 16px;
  right: 16px;
  bottom: 6px;
  height: 2px;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--color-secondary), var(--color-primary));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--transition-fast), opacity var(--transition-fast);
  opacity: 0;
}

.nav-link:hover {
  color: #fff;
  background: rgba(255, 255, 255, 0.06);
  text-decoration: none;
}

.nav-link:hover::before,
.nav-link.active::before {
  transform: scaleX(1);
  opacity: 1;
}

.nav-link.active {
  color: #fff;
  background: rgba(255, 255, 255, 0.1);
  box-shadow: 0 0 0 1px rgba(255, 255, 255, 0.12) inset;
}

.nav-dropdown .nav-link::after {
  content: '';
  border: 4px solid transparent;
  border-top-color: currentColor;
  margin-left: 4px;
}

/* 下拉菜单 */
.dropdown-menu {
  position: absolute;
  top: calc(100% + 4px);
  left: 0;
  list-style: none;
  padding: 12px;
  margin: 0;
  min-width: 210px;
  border-radius: var(--radius-lg);
  background: rgba(8, 18, 46, 0.95);
  border: 1px solid rgba(255, 255, 255, 0.08);
  box-shadow: var(--shadow-soft);
  opacity: 0;
  transform: translateY(-10px);
  pointer-events: none;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
  transition-delay: 0.12s;
}

.nav-dropdown:hover .dropdown-menu,
.nav-dropdown:focus-within .dropdown-menu,
.nav-dropdown.dropdown-open .dropdown-menu {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
  transition-delay: 0s;
}

.dropdown-menu li a {
  display: block;
  padding: 10px 14px;
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
  transition: background var(--transition-fast), color var(--transition-fast);
}

.dropdown-menu li a:hover {
  background: rgba(255, 255, 255, 0.05);
  color: #fff;
}

/* Header Actions */
.mobile-menu-btn {
  display: none;
  width: 46px;
  height: 46px;
  border-radius: var(--radius-lg);
  border: 1px solid rgba(255, 255, 255, 0.18);
  background: transparent;
  position: relative;
  cursor: pointer;
}

.mobile-menu-btn span {
  position: absolute;
  left: 12px;
  right: 12px;
  height: 2px;
  background: #fff;
  border-radius: 4px;
  transition: transform 0.3s ease, opacity 0.3s ease;
}

.mobile-menu-btn span:nth-child(1) { top: 14px; }
.mobile-menu-btn span:nth-child(2) { top: 22px; }
.mobile-menu-btn span:nth-child(3) { top: 30px; }

.mobile-menu-btn.active span:nth-child(1) {
  transform: translateY(8px) rotate(45deg);
}

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

.mobile-menu-btn.active span:nth-child(3) {
  transform: translateY(-8px) rotate(-45deg);
}

/* ========== 页脚 ========== */
.footer {
  position: relative;
  background: radial-gradient(circle at top, rgba(30, 136, 229, 0.25), transparent 55%), #020710;
  padding: var(--spacing-5xl) 0 var(--spacing-3xl);
  color: var(--color-text);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

.footer::before {
  content: '';
  position: absolute;
  inset: 0;
  background: url('../images/solution_traffic_monitoring.png') center/cover;
  opacity: 0.04;
  mix-blend-mode: screen;
  pointer-events: none;
}

.footer-content {
  position: relative;
}

.footer .grid {
  gap: var(--spacing-3xl);
}

.footer-title {
  font-size: 18px;
  margin-bottom: var(--spacing-xl);
  letter-spacing: 0.05em;
}

.footer p {
  color: var(--color-text-muted);
}

.footer-links {
  list-style: none;
  margin: 0;
  padding: 0;
}

.footer-links li {
  margin-bottom: var(--spacing-md);
}

.footer-links a {
  color: var(--color-text-muted);
  transition: color var(--transition-fast), padding-left var(--transition-fast);
}

.footer-links a:hover {
  color: #fff;
  padding-left: 6px;
}

.social-links {
  display: flex;
  gap: var(--spacing-md);
}

.social-icon {
  width: 42px;
  height: 42px;
  border-radius: 14px;
  border: 1px solid rgba(255, 255, 255, 0.15);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  transition: transform var(--transition-fast), border-color var(--transition-fast);
}

.social-icon:hover {
  transform: translateY(-4px);
  border-color: var(--color-secondary);
}

.footer-bottom {
  margin-top: var(--spacing-4xl);
  padding-top: var(--spacing-2xl);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-lg);
  justify-content: space-between;
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
}

.footer-links-bottom a {
  color: var(--color-text-muted);
  margin-left: var(--spacing-md);
}

.footer-links-bottom a:hover {
  color: #fff;
}

/* 返回顶部按钮 */
.back-to-top {
  position: fixed;
  right: 30px;
  bottom: 40px;
  width: 54px;
  height: 54px;
  border-radius: 18px;
  border: none;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: #fff;
  box-shadow: var(--shadow-glow);
  cursor: pointer;
  transform: translateY(20px);
  opacity: 0;
  visibility: hidden;
  transition: transform var(--transition-fast), opacity var(--transition-fast);
  z-index: 900;
}

.back-to-top.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

/* ========== 响应式 ========== */
@media (max-width: 1200px) {
  .navbar-menu {
    padding: 6px;
    gap: 4px;
  }
}

@media (max-width: 980px) {
  .navbar-wrapper {
    grid-template-columns: 1fr auto;
  }

  .navbar-menu {
    position: absolute;
    top: calc(100% + 18px);
    left: clamp(1rem, 6vw, 4rem);
    right: clamp(1rem, 6vw, 4rem);
    flex-direction: column;
    padding: 18px;
    background: rgba(5, 13, 31, 0.98);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: var(--radius-xl);
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-base);
  }

  .navbar-menu.active {
    max-height: 520px;
  }

  .nav-item {
    width: 100%;
  }

  .nav-link {
    width: 100%;
    justify-content: space-between;
  }

  .dropdown-menu {
    position: static;
    background: rgba(255, 255, 255, 0.02);
    border: none;
    box-shadow: none;
    padding: 8px 0 0 18px;
    max-height: 0;
    overflow: hidden;
    opacity: 1;
    transform: none;
  }

  .nav-dropdown.active .dropdown-menu {
    max-height: 400px;
  }

  .mobile-menu-btn {
    display: block;
    justify-self: end;
  }
}

@media (max-width: 640px) {
  .footer .grid {
    grid-template-columns: 1fr;
  }

  .footer-bottom {
    flex-direction: column;
  }

  .back-to-top {
    right: 16px;
    bottom: 24px;
  }
}