css实现自适应屏幕高度；

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
body,html{
margin:0px;
height:100%;
}
.div1{
width:100px;
height:100%;
background:red;
}
</style>
</head>
<body>
<div class="div1">

</div>
</body>
</html>