怎么能让报名参加的图片在下面空白区域垂直居中
<!DOCTYPE html>
<html>
<head>
<meta name="viewport"
content="width=device-width,initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no, viewport-fit=cover" />
<meta charset="UTF-8" />
<meta name="format-detection" content="telephone=no" />
<title>臻享活动</title>
<link rel="stylesheet" type="text/css" href="css/reset.css" />
<link rel="stylesheet" type="text/css" href="css/enjoyDetail.css" />
</head>
<body>
<div class="enjoy">
<div class="enjoy_logo">
<img src="./imagess/zxxq_bg.png" alt="">
</div>
<div class="enjoy_btn">
<img src="./imagess/zxxq_btn.png" alt="" onclick="enter()">
</div>
</div>
<script src="./js/main.js"></script>
<script src="./js/jquery-1.9.1.min.js"></script>
<script src="./js/enjoyDetail.js"></script>
</body>
</html>
.enjoy{
background-color: white;
width: 100%;
}
.enjoy .enjoy_logo img{
width: 100%;
height: 100%;
}
.enjoy .enjoy_btn{
margin-top: 0.6rem;
display: flex;
justify-content: center;
}
.enjoy .enjoy_btn img{
width: 5.22rem;
height: 1.04rem;
}