老师，请问内容如何设置百分之百，撑起内容的高度？

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>幕课网双列布局</title>
<style type="text/css">
*{
margin:0;
}
.total{
background-color:#80ffff;
}
.top{
width:100%;
height:100px;
background-color:#000;

}
.right{
float:right;
line-height:100px;
}
.right a{
text-decoration:none;
font-size:25px;
color: #ffffff;
padding:20px;
}
.content{
width:70%;
height:auto;
margin:0 auto;
padding-top:100px;
font-weight:900;
}
.left-one{
width:65%;
height:auto;
}
.left-one h2{
margin-bottom:10px;
}
.left-one p{
margin:10px 0;
}
.left-one p span{
margin-right:20px;
background-color:#ff9d6f;
}
.right-one{
float:right;
margin:-179px 200px 0 0;
}
.right-one h2{
margin-bottom:18px;
}
.right-one p{
margin:18px 0;
}
.right-one p span{
margin-right:15px;
}
.bottom{
width:100%;
height:100px;
background-color:#000;
margin-bottom:0;
text-align:center;
line-height:100px;
}
.bottom a{
text-decoration:none;
font-size:25px;
color:#fff;
padding:0 20px;
}
</style>
</head>
<body>
<div class="total">
<div class="top">
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<div class="content">
<div class="left-one">
<h2>课程推荐</h2>
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<h2>相关课程</h2>
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</body>
</html>