/* 更全面的重置 */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* 导航栏主容器 */
.navbar {
  background-color: #1d65a0;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
  position: sticky;
  top: 0;
  z-index: 1000;
}

/* 导航栏内容容器 */
.nav-container {
  max-width: 1440px;
  margin: 0 auto;
  padding: 0 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 80px;
}

/* Logo样式 */
.logo {
  display: flex;
  align-items: center;
  text-decoration: none;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.logo img {
  width: 150px;
  height: auto;
  display: block;
}

/* 导航菜单 */
.nav-menu {
  display: flex;
  list-style: none;
  gap: 2.5rem;
  align-items: center;
}

/* 导航链接 */
.nav-link {
  text-decoration: none;
  color: #ffffff;
  font-size: 1rem;
  font-weight: 500;
  position: relative;
  padding: 0.5rem 0;
  display: inline-block;
}

/* 悬停效果 - 下划线动画 */
.nav-link::after {
  content: '';
  position: absolute;
  bottom: -5px;
  left: 0;
  width: 0;
  height: 3px;
  background-color: #3498db;
  border-radius: 2px;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

/* 悬停时文字颜色变化 */
.nav-link:hover,
.nav-link:focus {
  outline: none;
}

/* 移动端菜单按钮 */
.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  cursor: pointer;
  padding: 0.5rem;
  background: none;
  border: none;
  gap: 4px;
}

.mobile-menu-toggle span {
  width: 25px;
  height: 3px;
  background-color: #ffffff;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  border-radius: 2px;
  transform-origin: center;
}

/* 汉堡菜单动画 */
.mobile-menu-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

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

.mobile-menu-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translate(7px, -6px);
}

/* 响应式设计 */
@media (max-width: 900px) {
  .nav-menu {
    gap: 1.3rem;
  }
}

@media (max-width: 768px) {
  .nav-container {
    padding: 0 1.3rem;
    height: 70px;
  }

  .mobile-menu-toggle {
    display: flex;
  }

  .nav-menu {
    position: fixed;
    left: -100%;
    top: 70px;
    flex-direction: column;
    background-color: #ffffff;
    width: 100%;
    text-align: center;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 10px 27px rgba(0, 0, 0, 0.05);
    padding: 1rem 0;
    gap: 0;
  }

  .nav-menu.active {
    left: 0;
  }

  .nav-menu li {
    width: 100%;
  }

  .nav-link {
    display: block;
    color: #1d65a0;
    padding: 1rem;
    width: 100%;
  }

  .nav-link:hover,
  .nav-link:focus {
    background-color: rgba(29, 101, 160, 0.05);
    color: #1d65a0;
  }

  .logo img {
    width: 120px;
  }

  /* 移动端移除下划线动画 */
  .nav-link::after {
    display: none;
  }

  /* 当前页面高亮 */
  .nav-link.active {
    background-color: #1d65a0;
    color: #ffffff;
  }
}

/* 减少动画偏好设置 */
@media (prefers-reduced-motion: reduce) {
  * {
    transition: none !important;
  }
}

/* 焦点可见性 */
.nav-link:focus-visible {
  outline: 2px solid #3498db;
  outline-offset: 2px;
}