适用场景:父子宽高都可未知(比较推荐这种方式,简单,而且目前兼容性也不错。)
<html>
<head>
<style>
.parent {
width: 100%;
height: 100px;
background: cyan;
display: flex;
justify-content: center;
align-items: center;
}
.son {
width: 20%;
height: 20%;
background: pink;
}
</style>
</head>
<body>
<div class='parent'>
<div class='son'></div>
</div>
</body>
</html>
适用场景:父元素宽高已知未知都行,但是首先得有宽高。其次子元素的宽高必须已知,因为需要设置子元素的负margin. (也可以将负margin设置成translate来做位移实现)
<html>
<head>
<style>
.parent {
position: relative;
width: 200px;
height: 200px;
background: pink;
}
.son {
position: absolute;
left: 50%;
top: 50%;
margin-left: -25px;
margin-top: -25px;
width: 50px;
height: 50px;
background: yellow;
}
</style>
</head>
<body>
<div class='parent'>
<div class='son'></div>
</div>
</body>
</html>
适用场景:父子元素宽高都未知的情况(该方式不需要明确知道子元素宽高,子元素宽高可用百分比,对于子元素宽高不确定需要居中的情况比较适合。)
<html>
<head>
<style>
.parent {
position: relative;
width: 200px;
height: 200px;
background: cyan;
}
.son {
position: absolute;
left: 0;
top: 0;
bottom: 0;
right: 0;
margin: auto;
width: 10%;
height: 10%;
background: yellow;
}
</style>
</head>
<body>
<div class='parent'>
<div class='son'></div>
</div>
</body>
</html>
适用场景:父子元素宽高未知,兼容性不大好
<html>
<head>
<style>
.parent {
display: grid;
}
.son {
jusitify-self: center;
align-self: center;
}
</style>
</head>
<body>
<div class='parent'>
<div class='son'></div>
</div>
</body>
</html>
适用场景: 父元素大小已知(非百分比高度),子元素大小未知,但子元素须为行内块元素,较好的兼容性
<html>
<head>
<style>
.parent {
display: table-cell;
vertical-align: middle;
text-align: center;
width: 100vw;
height: 90vh;
background-color: yellowgreen;
}
.son {
display: inline-block;
width: 200px;
height: 200px;
background-color: Indigo;
}
</style>
</head>
<body>
<div class='parent'>
<div class='son'></div>
</div>
</body>
</html>
适用场景:父子宽高都可未知,子元素需为行内块元素(这种方式其实就是使用伪元素的高度为100%,子元素和伪元素都设置 vertical-align: middle实现垂直居中的效果)
<html>
<head>
<style>
.parent {
height: 100vh;
width: 100vw;
text-align: center;
background: #c0c0c0;
}
.parent:before {
content: "\200B";
display: inline-block;
height: 100%;
vertical-align: middle;
}
.son {
display: inline-block;
vertical-align: middle;
width: 200px;
height: 200px;
padding: 10px 15px;
background: #f5f5f5;
}
</style>
</head>
<body>
<div class="parent">
<div class="son"></div>
</div>
</body>
</html>