1，flex 布局的方式：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>水平-垂直居中</title>
<style>
.con {
width: 400px;
height: 400px;
background-color: yellow;
margin: 100px auto;
/* flex 布局的方式 */
display: flex;
justify-content:center;
align-items:center;
}
.con .son {
width: 50px;
height: 50px;
background-color: red;
}
</style>
</head>
<body>
<div class="con">
<div class="son"></div>
</div>
</body>
</html>
2，子绝父相，transform 的 方式；
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>水平-垂直居中</title>
<style>
.con {
width: 400px;
height: 400px;
background-color: yellow;
margin: 100px auto;
/*子绝父相，transform 的 方式*/
position: relative;
}
.con .son {
width: 50px;
height: 50px;
background-color: red;
/*子绝父相，transform 的 方式*/
position: absolute;
top: 50%;
left:50%;
transform: translate(-50%, -50%);
}
</style>
</head>
<body>
<div class="con">
<div class="son"></div>
</div>
</body>
</html>
3，子绝父相，margin 一半的方式；
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>水平-垂直居中</title>
<style>
.con {
width: 400px;
height: 400px;
background-color: yellow;
margin: 100px auto;
/*子绝父相，margin一半的 方式*/
position: relative;
}
.con .son {
width: 50px;
height: 50px;
background-color: red;
/*子绝父相，margin一半的 方式*/
position: absolute;
top: 50%;
left:50%;
margin-top: -25px;
margin-left: -25px;
}
</style>
</head>
<body>
<div class="con">
<div class="son"></div>
</div>
</body>
</html>
4，绝对定位下top left right bottom 都设置0的方式
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>水平-垂直居中</title>
<style>
.con {
width: 400px;
height: 400px;
background-color: yellow;
margin: 100px auto;
/*绝对定位下top left right bottom 都设置0的方式*/
position: relative;
}
.con .son {
width: 50px;
height: 50px;
background-color: red;
/*子绝对定位下top left right bottom 都设置0的方式*/
position: absolute;
top: 0;
left:0;
right: 0;
bottom: 0;
margin: auto;
}
</style>
</head>
<body>
<div class="con">
<div class="son"></div>
</div>
</body>
</html>
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