水平垂直居中
用 CSS 实现水平垂直居中有很多方法，具体选择取决于你想要居中的元素类型和你支持的浏览器。以下是几种常见的方法及其对应的 CSS 代码：
1. 弹性布局
html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>弹性布局</title>
<style>
.container {
display: flex;
justify-content: center;
align-items: center;
height: 100vh;
border: 1px solid #ccc;
}
.box {
width: 100px;
height: 100px;
background-color: lightblue;
}
</style>
</head>
<body>
<div class="container">
<div class="box">中心</div>
</div>
</body>
</html>2. 网格布局
html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>网格布局</title>
<style>
.container {
display: grid;
place-items: center;
height: 100vh;
border: 1px solid #ccc;
}
.box {
width: 100px;
height: 100px;
background-color: lightgreen;
}
</style>
</head>
<body>
<div class="container">
<div class="box">中心</div>
</div>
</body>
</html>3. 定位+margin
html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>定位+margin</title>
<style>
.container {
position: relative;
height: 100vh;
border: 1px solid #ccc;
}
.box {
width: 100px;
height: 100px;
background-color: lightcoral;
position: absolute;
top: 0;
right: 0;
bottom: 0;
left: 0;
margin: auto;
}
</style>
</head>
<body>
<div class="container">
<div class="box">中心</div>
</div>
</body>
</html>4. 绝对布局
html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>绝对布局</title>
<style>
.container {
position: relative;
height: 100vh;
border: 1px solid #ccc;
}
.box {
width: 100px;
height: 100px;
background-color: lightcoral;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
}
</style>
</head>
<body>
<div class="container">
<div class="box">中心</div>
</div>
</body>
</html>5. 表格单元格
html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>表格单元格</title>
<style>
.container {
display: table;
width: 100%;
height: 100vh;
border: 1px solid #ccc;
}
.box {
display: table-cell;
vertical-align: middle;
text-align: center;
background-color: lightgoldenrodyellow;
}
</style>
</head>
<body>
<div class="container">
<div class="box">中心</div>
</div>
</body>
</html>6. 带有伪元素的内联块
html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>带有伪元素的内联块</title>
<style>
.container {
text-align: center;
height: 100vh;
border: 1px solid #ccc;
}
.container::before {
content: '';
display: inline-block;
height: 100%;
vertical-align: middle;
}
.box {
display: inline-block;
vertical-align: middle;
width: 100px;
height: 100px;
background-color: lightseagreen;
}
</style>
</head>
<body>
<div class="container">
<div class="box">中心</div>
</div>
</body>
</html>