doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>子元素在父元素里面垂直居中title>
<link rel="stylesheet" type="text/css" href=""/>
<style>
#d1{
position: relative;
border:thin solid red;
width:900px;
height:100px;
}
#d2{/*dashed也是虚线*/
border:thin dotted blue;
width:50px;
height:50px;
float:right;
}
.center-vertical{
position: relative;
top: 50%;
transform: translateY(-50%);
}
style>
head>
<body>
<div id="d1">
<div id="d2" class="center-vertical">div>
div>
body>
html>