仅为导航屏幕修改导航栏的背景颜色

问题描述

我的导航栏当前没有背景，但是在智能手机版本中，它看起来有些奇怪，因此我想知道是否有可能仅在小屏幕上放置白色背景。谢谢！

代码如下：

<nav class="navbar navbar-expand-md navbar-light fixed-top mt-4">
            <a class="navbar-brand ml-4" href="index.html">
                <img src="img/logo.png" width=100% alt="" loading="lazy">
            </a>
            <button class="navbar-toggler" data-toggle="collapse" data-target="#navbarMenu">
                <span class="navbar-toggler-icon "></span>
            </button>
            <div class="collapse navbar-collapse" id="navbarMenu">
                <ul class="navbar-nav ml-auto">
                    <li class="nav-item mr-4">
                        <a href="index.html" class="nav-link text-dark">home</a>
                    </li>
                    <li class="nav-item mr-4">
                        <div class="dropdown show">
                            <a class="btn btn-secondary dropdown-toggle" href="#" role="button" id="dropdownMenuLink"
                                data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                                progetti
                            </a>
                            <div class="dropdown-menu" aria-labelledby="dropdownMenuLink">

                                <a class="dropdown-item" href="graphicdesign.html">01. Graphic Design</a>
                                <a class="dropdown-item" href="videografica.html">02. Videografica</a>
                            </div>
                    </li>
                    <li class="nav-item mr-4">
                        <a href="chisono.html" class="nav-link text-dark ">chi sono?</a>
                    </li>
                    <li class="nav-item mr-1">
                        <a href="contattami.html" class="nav-link text-dark">contattami</a>
                    </li>
                </ul>
            </div>
        </nav>

解决方法

使用媒体查询对其进行修复。

@media (max-width: 575.98px) { 

   // some style include here
  .navbar.navbar-expand-md.navbar-light{background:#111;}
  .navbar.navbar-expand-md.navbar-light .navbar-toggler{background:#fff;}
}

@media (max-width: 575.98px) { 

   // some style include here
  .navbar.navbar-expand-md.navbar-light{background:#111;}
  .navbar.navbar-expand-md.navbar-light .navbar-toggler{background:#fff;}
}

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>

<nav class="navbar navbar-expand-md navbar-light fixed-top mt-4">
    <a class="navbar-brand ml-4" href="index.html">
        <img src="img/logo.png" width=100% alt="" loading="lazy">
    </a>
    <button class="navbar-toggler" data-toggle="collapse" data-target="#navbarMenu">
        <span class="navbar-toggler-icon "></span>
    </button>
    <div class="collapse navbar-collapse" id="navbarMenu">
        <ul class="navbar-nav ml-auto">
            <li class="nav-item mr-4">
                <a href="index.html" class="nav-link text-dark">home</a>
            </li>
            <li class="nav-item mr-4">
                <div class="dropdown show">
                    <a class="btn btn-secondary dropdown-toggle" href="#" role="button" id="dropdownMenuLink"
                        data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                        progetti
                    </a>
                    <div class="dropdown-menu" aria-labelledby="dropdownMenuLink">

                        <a class="dropdown-item" href="graphicdesign.html">01. Graphic Design</a>
                        <a class="dropdown-item" href="videografica.html">02. Videografica</a>
                    </div>
            </li>
            <li class="nav-item mr-4">
                <a href="chisono.html" class="nav-link text-dark ">chi sono?</a>
            </li>
            <li class="nav-item mr-1">
                <a href="contattami.html" class="nav-link text-dark">contattami</a>
            </li>
        </ul>
    </div>
</nav>

,

使用@media (<specified width>) {...}执行此操作。在此示例中，我将其设置为更大的屏幕。您可以在这里阅读有关media queries的更多信息：https://getbootstrap.com/docs/4.5/layout/overview/#responsive-breakpoints

@media (max-width: 992px) {
  .navbar-nav {
    background: red;
  }
}

<head>
  <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css" integrity="sha384-JcKb8q3iqJ61gNV9KGb8thSsNjpSL0n8PARn9HuZOnIxN0hoP+VmmDGMN5t9UJ0Z" crossorigin="anonymous">
</head>
<body>
  <nav class="navbar navbar-expand-md navbar-light fixed-top mt-4">
    <a class="navbar-brand ml-4" href="index.html">
      <img src="img/logo.png" width=100% alt="" loading="lazy">
    </a>
    <button class="navbar-toggler" data-toggle="collapse" data-target="#navbarMenu">
      <span class="navbar-toggler-icon "></span>
    </button>
    <div class="collapse navbar-collapse" id="navbarMenu">
      <ul class="navbar-nav ml-auto">
        <li class="nav-item mr-4">
          <a href="index.html" class="nav-link text-dark">home</a>
        </li>
        <li class="nav-item mr-4">
          <div class="dropdown show">
            <a class="btn btn-secondary dropdown-toggle" href="#" role="button" id="dropdownMenuLink"
                    data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                    progetti
            </a>
            <div class="dropdown-menu" aria-labelledby="dropdownMenuLink">
              <a class="dropdown-item" href="graphicdesign.html">01. Graphic Design</a>
              <a class="dropdown-item" href="videografica.html">02. Videografica</a>
            </div>
          </div>
        </li>
        <li class="nav-item mr-4">
          <a href="chisono.html" class="nav-link text-dark ">chi sono?</a>
        </li>
        <li class="nav-item mr-1">
          <a href="contattami.html" class="nav-link text-dark">contattami</a>
        </li>
      </ul>
    </div>
  </nav>

  <script src="https://code.jquery.com/jquery-3.5.1.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
  <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/umd/popper.min.js" integrity="sha384-9/reFTGAW83EW2RDu2S0VKaIzap3H66lZH81PoYlFhbGU+6BZp6G7niu735Sk7lN" crossorigin="anonymous"></script>
  <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/js/bootstrap.min.js" integrity="sha384-B4gt1jrGC7Jh4AgTPSdUtOBvfO8shuf57BaghqFfPlYxofvL8/KUEfYiJOMMV+rV" crossorigin="anonymous"></script>
</body>