SOURCE

<div class="shadow">
	<div class="login">
		<img src="https://cdns.jsrun.top/avatar/default.png" alt="">
    </div>
</div>

.shadow {
    background: #ccddee;
    width:  100%;
    height: 100%;
    position: absolute;
}

.login {
    position: relative;
    left: 50%;
    top: 50%;
    margin-left: -100px;
    margin-top: -100px;
}

img {
    width: 200px;
    height: 200px;
    display: block;
}

body {
    margin: 0px;
    padding: 0px;
}