使用flexbox垂直居中

时间：2017-03-26 23:30:54

标签： html css css3 flexbox

我目前在垂直居中包装时遇到问题。我尝试创建一个显示flex的div，并按照另一个帖子的建议对齐项目中心，但它没有工作。任何想法为什么以及如何解决它？

＆＃13;
＆＃13; 
body {
  font-family: Arial, sans-serif;
  background: #ddd;
}

h1 {
  text-align: center;
  font-family: "Trebuchet MS", Tahoma, Arial, sans-serif;
  color: #333;
  text-shadow: 0 1px 0 #fff;
  margin: 50px 0;
}

#center {
  display: flex;
  align-items: center;
}

#wrapper {
  width: 100px;
  margin: 0 auto;
  background: #fff;
  padding: 20px;
  border: 10px solid #aaa;
  border-radius: 15px;
  background-clip: padding-box;
  text-align: center;
}

.button {
  font-family: Helvetica, Arial, sans-serif;
  font-size: 13px;
  padding: 5px 10px;
  border: 1px solid #aaa;
  background-color: #eee;
  background-image: linear-gradient(top, #fff, #f0f0f0);
  border-radius: 2px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.15);
  color: #666;
  text-decoration: none;
  text-shadow: 0 1px 0 #fff;
  cursor: pointer;
  transition: all 0.2s ease-out;
}

.button:hover {
  border-color: #999;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.25);
}

.button:active {
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.25) inset;
}

.overlay {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  background: rgba(0, 0, 0, 0.5);
  transition: opacity 200ms;
  visibility: hidden;
  opacity: 0;
}

.overlay.light {
  background: rgba(255, 255, 255, 0.5);
}

.overlay .cancel {
  position: absolute;
  width: 100%;
  height: 100%;
  cursor: default;
}

.overlay:target {
  visibility: visible;
  opacity: 1;
}

.popup {
  margin: 75px auto;
  padding: 20px;
  background: #fff;
  border: 1px solid #666;
  width: 300px;
  box-shadow: 0 0 50px rgba(0, 0, 0, 0.5);
  position: relative;
}

.light .popup {
  border-color: #aaa;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.25);
}

.popup h2 {
  margin-top: 0;
  color: #666;
  font-family: "Trebuchet MS", Tahoma, Arial, sans-serif;
}

.popup .close {
  position: absolute;
  width: 20px;
  height: 20px;
  top: 20px;
  right: 20px;
  opacity: 0.8;
  transition: all 200ms;
  font-size: 24px;
  font-weight: bold;
  text-decoration: none;
  color: #666;
}

.popup .close:hover {
  opacity: 1;
}

.popup .content {
  max-height: 400px;
  overflow: auto;
}

.popup p {
  margin: 0 0 1em;
}

.popup p:last-child {
  margin: 0;
}

iframe {
  border: none;
}
＆＃13; 
<div id="center">
  <div id="wrapper">
    <p><a class="button" href="#popup1">Click Me</a></p>
  </div>

  <div id="popup1" class="overlay">
    <div class="popup">
      <h2>Drop Day</h2>
      <a class="close" href="#">&times;</a>
      <div class="content">
        <p>Hello</p>
      </div>
    </div>
  </div>
</div>
＆＃13;
＆＃13;
＆＃13;

1 个答案:

答案 0 :(得分：2)

您的主包装（div＃center）必须定义其高度：

       body {
            font-family: Arial, sans-serif;
            background: #ddd;
        }
        
        h1 {
            text-align: center;
            font-family: "Trebuchet MS", Tahoma, Arial, sans-serif;
            color: #333;
            text-shadow: 0 1px 0 #fff;
            margin: 50px 0;
        }
        
        #center {
            display: flex;
            align-items: center;
            /* or any other height you want */
            height: 100vh; 
        }
        
        #wrapper {
            width: 100px;
            margin: 0 auto;
            background: #fff;
            padding: 20px;
            border: 10px solid #aaa;
            border-radius: 15px;
            background-clip: padding-box;
            text-align: center;
        }
        
        .button {
            font-family: Helvetica, Arial, sans-serif;
            font-size: 13px;
            padding: 5px 10px;
            border: 1px solid #aaa;
            background-color: #eee;
            background-image: linear-gradient(top, #fff, #f0f0f0);
            border-radius: 2px;
            box-shadow: 0 1px 3px rgba(0, 0, 0, 0.15);
            color: #666;
            text-decoration: none;
            text-shadow: 0 1px 0 #fff;
            cursor: pointer;
            transition: all 0.2s ease-out;
        }
        
        .button:hover {
            border-color: #999;
            box-shadow: 0 1px 3px rgba(0, 0, 0, 0.25);
        }
        
        .button:active {
            box-shadow: 0 1px 3px rgba(0, 0, 0, 0.25) inset;
        }
        
        .overlay {
            position: absolute;
            top: 0;
            bottom: 0;
            left: 0;
            right: 0;
            background: rgba(0, 0, 0, 0.5);
            transition: opacity 200ms;
            visibility: hidden;
            opacity: 0;
        }
        
        .overlay.light {
            background: rgba(255, 255, 255, 0.5);
        }
        
        .overlay .cancel {
            position: absolute;
            width: 100%;
            height: 100%;
            cursor: default;
        }
        
        .overlay:target {
            visibility: visible;
            opacity: 1;
        }
        
        .popup {
            margin: 75px auto;
            padding: 20px;
            background: #fff;
            border: 1px solid #666;
            width: 300px;
            box-shadow: 0 0 50px rgba(0, 0, 0, 0.5);
            position: relative;
        }
        
        .light .popup {
            border-color: #aaa;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.25);
        }
        
        .popup h2 {
            margin-top: 0;
            color: #666;
            font-family: "Trebuchet MS", Tahoma, Arial, sans-serif;
        }
        
        .popup .close {
            position: absolute;
            width: 20px;
            height: 20px;
            top: 20px;
            right: 20px;
            opacity: 0.8;
            transition: all 200ms;
            font-size: 24px;
            font-weight: bold;
            text-decoration: none;
            color: #666;
        }
        
        .popup .close:hover {
            opacity: 1;
        }
        
        .popup .content {
            max-height: 400px;
            overflow: auto;
        }
        
        .popup p {
            margin: 0 0 1em;
        }
        
        .popup p:last-child {
            margin: 0;
        }
        
        iframe {
            border: none;
        }
<html>

<head>
    <meta charset="UTF-8">
    <meta content='width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0' name='viewport'>
</head>

<body>
    <div id="center">
        <div id="wrapper">
            <p><a class="button" href="#popup1">Click Me</a></p>
        </div>

        <div id="popup1" class="overlay">
            <div class="popup">
                <h2>Drop Day</h2>
                <a class="close" href="#">&times;</a>
                <div class="content">
                    <p>Hello</p>
                </div>
            </div>
        </div>
    </div>

</body>

</html>

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