When using flex element layout, the child can not set the height of how to do?

1. Using absolute positioning

html

	<div class="wrap">  
        <div class="header">头部</div>  
        <div class="main">  
            <div class="container">内容</div>  
        </div>  
        <div class="footer">尾部</div>  
    </div>

css

html,body{
	width:100%;
	height:100%;
}
.wrap{
	width:100%;
	height:100%;
}
.header,.footer{
	height:40px;
}
.main{
	display:flex;
	postion:relative;
}
.container{
	position:absolute;
	width:100%;
	height:100%;
}

other

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