css - 在 bootstrap 4 中为事件导航栏链接下划线

Question

我正在将网站从 bootstrap 3 升级到 4(测试版)。我用来强调事件导航栏链接的 css 不再有效。它不是在元素下划线，而是在页面的整个宽度下划线。如何在 bootstrap 4 中为事件导航项加下划线？

Bootstrap 3 CSS

.navbar-default .navbar-nav > .active:after {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    content: " ";
    border-bottom: 5px solid #5BC0EB;
}

尝试使用 Bootstrap 4 css

.navbar-light .navbar-nav .active::after {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    content: " ";
    border-bottom: 5px solid #5BC0EB;
}

HTML

<nav class="navbar fixed-top navbar-light bg-light navbar-expand-md">
    <div class="container">
        <a class="navbar-brand" href="#">My Website</a>

        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarCollapse" aria-controls="navbarCollapse"
            aria-expanded="false" aria-label="Toggle navigation">
                <span class="navbar-toggler-icon"></span>
        </button>

        <div class="collapse navbar-collapse justify-content-end" id="main-nav-collapse">
            <ul class="navbar-nav">
                <li class="nav-item active"><a class="nav-link" href="#about">About</a></li>
                <li class="nav-item"><a class="nav-link" href="#classes">Classes</a></li>
                <li class="nav-item"><a class="nav-link" href="#gallery">Gallery</a></li>
                <li class="nav-item"><a class="nav-link" href="#events">Events</a></li>
                <li class="nav-item"><a class="nav-link" href="#contact">Contact</a></li>
                <li class="nav-item"><a class="nav-link" href="#offers">Offers</a></li>
            </ul>
        </div>
    </div>
</nav>

Answer 1

这是因为您的定位。

尝试将 relative 位置设置为您的 li 并将 after 设置为 li 内的 a 标记，这将是absolute 定位如下

.navbar-nav > li {
  float: left;
  position: relative;
}
.navbar-light .navbar-nav .active a::after {
  border-bottom: 5px solid #5bc0eb;
  bottom: -10px;
  content: " ";
  left: 0;
  position: absolute;
  right: 0;
}

希望对您有所帮助。