bootstrap navbar 置顶 设置背景颜色

对于Bootstrap中的navbar置顶，您可以在nav元素上添加class=“fixed-top”来实现。至于设置背景颜色，您可以在CSS中添加样式，例如background-color: #f8f9fa;来改变navbar的背景颜色。完整代码示例如下：

<nav class="navbar navbar-expand-lg navbar-light bg-light fixed-top">
<a class="navbar-brand" href="#">Logo</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarNav">
<ul class="navbar-nav">
<li class="nav-item active">
<a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">About</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Contact</a>
</li>
</ul>
</div>
</nav>

CSS样式：

.navbar {
background-color: #f8f9fa;
}