Html 我不知道'；我不知道导航栏为什么不固定

我已经建立了一个带有引导的登录页，由于某些原因，导航栏没有固定。下面是导航栏的代码

<nav class="navbar fixed-top navbar-inverse bg-primary navbar-toggleable-md navbar-light bg-faded">
<div class="container">
<button class="navbar-toggler navbar-toggler-right" 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 mr-auto">
      <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="#">Features</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Pricing</a>
      </li>
    </ul>
  </div>
<a class="navbar-brand pull-sm-right mr-10" href="#">Aquastars Swimming  School</a>
</div>
</nav>

您的代码运行良好，因为您使用的是bootstrap 4。 您可以在这里看到代码的工作演示

您是否使用浏览器检查元素以查看CSS样式是如何应用的？当我滚动导航栏时，导航栏会滚动且未固定。@AltBrian您错过了

导航栏固定顶部

class man！谢谢古德伯森。

<nav class="navbar fixed-top navbar-inverse bg-primary navbar-toggleable-md navbar-light bg-faded">
<div class="container">
<button class="navbar-toggler navbar-toggler-right" 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 mr-auto">
      <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="#">Features</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Pricing</a>
      </li>
    </ul>
  </div>
<a class="navbar-brand pull-sm-right mr-10" href="#">Aquastars Swimming  School</a>
</div>
</nav>