Bootstrap 4背景图像全高，导航栏无滚动答案

【问题标题】：Bootstrap 4 background image full-height with navbar no scrollingBootstrap 4背景图像全高，导航栏无滚动
【发布时间】：2018-09-02 05:55:57
【问题描述】：

我有一个带有导航栏的页面。我想向页面（不是导航栏）添加响应式背景图像。

如果我将页面设置为 100% 高度，它会用滚动条溢出页面。

这应该如何实现？我不知道。

.bg { 
    /* The image used */
    background-image: url("http://via.placeholder.com/350x150");


    /* Center and scale the image nicely */
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
}

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet"/>

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</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="#">Features</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Pricing</a>
      </li>
      <li class="nav-item">
        <a class="nav-link disabled" href="#">Disabled</a>
      </li>
    </ul>
  </div>
</nav>

<div class="main-page">
  <div class="bg"></div>
  <div class="data">
    bla bla bla
  </div>

</div>

编辑：jsfiddle - JSFIDDLE

【问题讨论】：

标签： html css twitter-bootstrap bootstrap-4 background-image

【解决方案1】：

您可以使用 Bootstrap 4 flexbox 工具，并将 flex:1 1 auto 添加到 main-page 以填充高度（无需滚动）。

https://www.codeply.com/go/isN2cS0m0q

<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"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" ></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"></script>
    
<style>
body {
    min-height: 100vh;
}
.flex-fill {
   flex: 1 1 auto;
}  
.bg { 
    background-image: url("http://placehold.it/350x150");
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
}
</style>
<body class="d-flex flex-column">
<nav class="navbar navbar-expand-lg navbar-light bg-light">
    <a class="navbar-brand" href="#">Navbar</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="#">Features</a>
            </li>
            <li class="nav-item">
                <a class="nav-link" href="#">Pricing</a>
            </li>
            <li class="nav-item">
                <a class="nav-link disabled" href="#">Disabled</a>
            </li>
        </ul>
    </div>
</nav>
<div class="main-page d-flex flex-column flex-fill">
    <div class="bg flex-fill"></div>
    <div class="data">
        bla bla bla
    </div>
</div>
</body>

注意：flex-fill 类将是 included in Bootstrap 4.1，因此在 4.1 发布时将不再需要 flex-fill 的额外 CSS。

【讨论】：

【解决方案2】：

将以下 css 规则添加到您的 .bg 类：

height: calc(100vh - 56px)

这将计算高度（100% 视口高度减去 56px 的导航栏高度）。

工作代码sn-p：

<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>
    
<style>
.bg { 
    /* The image used */
    background-image: url("http://via.placeholder.com/350x150");


    /* Center and scale the image nicely */
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
    height: calc(100vh - 56px);
}
</style>

<nav class="navbar navbar-expand-lg navbar-light bg-light">
    <a class="navbar-brand" href="#">Navbar</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="#">Features</a>
            </li>
            <li class="nav-item">
                <a class="nav-link" href="#">Pricing</a>
            </li>
            <li class="nav-item">
                <a class="nav-link disabled" href="#">Disabled</a>
            </li>
        </ul>
    </div>
</nav>

<div class="main-page">
    <div class="bg"></div>
    <div class="data">
        bla bla bla
    </div>

</div>

【讨论】：

这迫使你在两个地方依赖导航栏的高度。如果我现在更改导航栏高度，我也必须在这里更改它