将叠加层的内容放在中间

时间：2017-04-04 08:35:53

标签： javascript html css overlay

目标：
叠加内容应位于页面中间。

问题：
我无法将叠加内容（白框）放在中间。我错过了什么语法？

谢谢！ 

function openNav() {
    document.getElementById("myNav").style.height = "100%";
}

function closeNav() {
    document.getElementById("myNav").style.height = "0%";
}
body {
    margin: 0;
    font-family: 'Lato', sans-serif;
}

.overlay {
    height: 0%;
    width: 100%;
    position: fixed;
    z-index: 1;
    top: 0;
    left: 0;
    background-color: rgb(0,0,0);
    background-color: rgba(0,0,0, 0.8);
    overflow-y: hidden;
    transition: 0.5s;
}

.overlay-content {
    position: relative;
    top: 10%;
    width: 70%;
    text-align: left;
    margin-top: 30px;
  background: white
}

.overlay a {
    padding: 8px;
    text-decoration: none;
    font-size: 36px;
    color: #818181;
    display: block;
    transition: 0.3s;
}

.overlay a:hover, .overlay a:focus {
    color: #f1f1f1;
}

.overlay .closebtn {
    position: absolute;
    top: 20px;
    right: 45px;
    font-size: 60px;
}

@media screen and (max-height: 450px) {
  .overlay {overflow-y: auto;}
  .overlay a {font-size: 20px}
  .overlay .closebtn {
    font-size: 40px;
    top: 15px;
    right: 35px;
  }
}
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<body>

<div id="myNav" class="overlay">
  <a href="javascript:void(0)" class="closebtn" onclick="closeNav()">&times;</a>
  <div class="overlay-content">
    <a href="#">About</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">Contact</a>
  </div>
</div>

<h2>Fullscreen Overlay Nav Example</h2>
<p>Click on the element below to open the fullscreen overlay navigation menu.</p>
<p>In this example, the navigation menu will slide downwards from the top:</p>
  
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<span style="font-size:30px;cursor:pointer" onclick="openNav()">&#9776; open</span>  

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</body>
</html>

3 个答案:

答案 0 :(得分：0)

使用CSS3 translateY使可变高度元素在屏幕上居中。

function openNav() {
    document.getElementById("myNav").style.height = "100%";
}

function closeNav() {
    document.getElementById("myNav").style.height = "0%";
}
body {
    margin: 0;
    font-family: 'Lato', sans-serif;
}

.overlay {
    height: 0%;
    width: 100%;
    position: fixed;
    z-index: 1;
    top: 0;
    left: 0;
    background-color: rgb(0,0,0);
    background-color: rgba(0,0,0, 0.8);
    overflow-y: hidden;
    transition: 0.5s;
}

.overlay-content {
    position: relative;
    top: 50%;
    transform: translateY(-50%) translateX(-50%);
    width: 70%;
    left: 50%;
    text-align: left;
    background: white;
}

.overlay a {
    padding: 8px;
    text-decoration: none;
    font-size: 36px;
    color: #818181;
    display: block;
    transition: 0.3s;
}

.overlay a:hover, .overlay a:focus {
    color: #f1f1f1;
}

.overlay .closebtn {
    position: absolute;
    top: 20px;
    right: 45px;
    font-size: 60px;
}

@media screen and (max-height: 450px) {
  .overlay {overflow-y: auto;}
  .overlay a {font-size: 20px}
  .overlay .closebtn {
    font-size: 40px;
    top: 15px;
    right: 35px;
  }
}
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<body>

<div id="myNav" class="overlay">
  <a href="javascript:void(0)" class="closebtn" onclick="closeNav()">&times;</a>
  <div class="overlay-content">
    <a href="#">About</a>
    <a href="#">Services</a>
    <a href="#">Clients</a>
    <a href="#">Contact</a>
  </div>
</div>

<h2>Fullscreen Overlay Nav Example</h2>
<p>Click on the element below to open the fullscreen overlay navigation menu.</p>
<p>In this example, the navigation menu will slide downwards from the top:</p>
  
<br/>  
<br/>  
<br/>  
<br/>  
<br/>  
<br/>  
<br/>    
<br/>  
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<br/>    
  <br/>  
<br/>  
<br/>  
<br/>  
<br/>  
<br/>  
<br/>    
   
<span style="font-size:30px;cursor:pointer" onclick="openNav()">&#9776; open</span>  

<br/>    
<br/>  
<br/>  
<br/>  
<br/>  
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<br/>  
<br/>    
  
</body>
</html>

答案 1 :(得分：0)

你可以试试这个：

.overlay-content {
   position: relative;
   top: 10%;
   width: 70%;
   text-align: left;
   margin: 30px auto;
   background: white
}

答案 2 :(得分：0)

<div id="myNav" class="overlay">
  <a href="javascript:void(0)" class="closebtn"   onclick="closeNav()">&times;</a>
 <div class="overlay-content">
   <a href="#">About</a>
   <a href="#">Services</a>
   <a href="#">Clients</a>
   <a href="#">Contact</a>
 </div>

嗨，我认为以上部分适用于您的叠加层。对？ 然后，您可以使用以下样式使叠加内容（白色框）位于中间。

.overlay {
   position: fixed;
   display: table;
   float: none;
   width: 100%;
   height: 100%;
   z-index: 1;
   background-color: rgba(0,0,0, 0.8);
   transition: 0.5s;
}

.overlay-content {
   vertical-align: middle;
   display: table-cell;
   margin: 0 auto;
   float: none;
   width: 70%;
   height: auto;
   text-align: left;
   background: #fff;
}
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