1 垂直居中总结
效果预览：
1.1 使用 flex 布局完成垂直居中
<!DOCTYPE html>
<html lang="en">
<head>
<style>
.container {
width: 300px;
height: 300px;
margin-left: 300px;
border: 1px solid #f00;
display: flex;
align-items: center;
justify-content: center;
}
.img_box {
width: 200px;
height: 200px;
}
.img_box > img {
width: 200px;
height: 200px;
}
</style>
</head>
<body>
<div class="container">
<div class="img_box">
<img src="./images/alsj.webp" alt="">
</div>
</div>
</body>
</html>
1.2 Display: table 完成水平垂直居中
<!DOCTYPE html>
<html lang="en">
<head>
<style>
.container {
width: 300px;
height: 300px;
margin-left: 300px;
border: 1px solid #f00;
display: table;
}
.img_box {
width: 200px;
height: 200px;
display: table-cell;
vertical-align: middle;
text-align: center;
}
.img_box > img {
width: 200px;
height: 200px;
}
</style>
</head>
<body>
<div class="container">
<div class="img_box">
<img src="./images/alsj.webp" alt="">
</div>
</div>
</body>
</html>
1.3 用绝对定位完成水平垂直居中（兼容性好）
<!DOCTYPE html>
<html lang="en">
<head>
<style>
.container {
width: 300px;
height: 300px;
margin-left: 300px;
border: 1px solid #f00;
position: relative;
}
.img_box {
width: 200px;
height: 200px;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%,-50%);
}
.img_box > img {
width: 200px;
height: 200px;
}
</style>
</head>
<body>
<div class="container">
<div class="img_box">
<img src="./images/alsj.webp" alt="">
</div>
</div>
</body>
</html>
1.4 用 grid 布局完成水平垂直居中
<!DOCTYPE html>
<html lang="en">
<head>
<style>
.container {
width: 300px;
height: 300px;
margin-left: 300px;
border: 1px solid #f00;
display: grid;
place-items: center;
}
.img_box {
width: 200px;
height: 200px;
}
.img_box > img {
width: 200px;
height: 200px;
}
</style>
</head>
<body>
<div class="container">
<div class="img_box">
<img src="./images/alsj.webp" alt="">
</div>
</div>
</body>
</html>
1.5 单行文本的水平垂直居中
单行文本的水平垂直居中除了使用 flex 或 grid 布局实现外，还可以使用行高 line-height 来实现，效果如下：
代码：
<!DOCTYPE html>
<html lang="en">
<head>
<style>
.container {
width: 300px;
height: 300px;
margin-left: 300px;
border: 1px solid #f00;
}
.container p {
border: 1px solid #0f0;
height: 40px;
line-height: 40px;
text-align: center;
}
</style>
</head>
<body>
<div class="container">
<p>我是单行文本</p>
</div>
</body>
</html>
