官网导航更智能：CSS动画下划线，让每一次点击都充满期待！

<nav class="navbar">
        <ul>
            <li><a href="#">首页</a></li>
            <li>
                <a href="#">关于我们</a>
                <ul class="dropdown">
                    <li><a href="#">团队</a></li>
                    <li><a href="#">历史</a></li>
                    <li><a href="#">文化</a></li>
                </ul>
            </li>
            <li>
                <a href="#">服务</a>
                <ul class="dropdown">
                    <li><a href="#">咨询</a></li>
                    <li><a href="#">支持</a></li>
                    <li><a href="#">培训</a></li>
                </ul>
            </li>
            <li><a href="#">联系我们</a></li>
        </ul>
    </nav>

body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f0f0f0;
}
.navbar {
    background-color: #333;
    padding: 10px 0;
    text-align: center;
}
.navbar ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    position: relative;
}
.navbar ul li {
    margin: 0 15px;
    position: relative;
}
.navbar ul li a {
    color: white;
    text-decoration: none;
    font-size: 18px;
    position: relative;
    padding: 5px 0;
    transition: color 0.3s ease;
}
.navbar ul li a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    background-color: #007BFF;
    left: 50%;
    bottom: 0;
    transition: all 0.3s ease;
    transform: translateX(-50%);
}
.navbar ul li a::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 10px;
    height: 10px;
    background-color: #007BFF;
    border-radius: 50%;
    opacity: 0;
    transform: translate(-50%, -50%) scale(0.5);
    transition: opacity 0.3s ease, transform 0.3s ease;
}
.navbar ul li a:hover {
    color: #007BFF;
}
.navbar ul li a:hover::after {
    width: 100%;
}
.navbar ul li a:hover::before {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1.5);
    animation: bubble 1s ease-in-out infinite;
}
@keyframes bubble {
    0%, 100% {
        transform: translate(-50%, -50%) scale(1.5);
    }
    50% {
        transform: translate(-50%, -150%) scale(1);
        opacity: 0;
    }
}
.navbar ul li a:hover {
    color: #007BFF;
}
.navbar ul li a:hover::after {
    width: 100%;
}
.navbar ul li  .dropdown {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    background-color: #333;
    padding: 10px 0;
    border-radius: 5px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}
.dropdown li {
    padding: 10px 20px;
}
.dropdown li a {
    color: white;
    font-size: 16px;
    white-space: nowrap;
}
.navbar ul li:hover .dropdown {
    display: block;
}
.navbar ul li .dropdown li a:hover {
    color: #007BFF;
}