Top shadow

by infous

HTML

<div class="d"></div>

CSS

body {
    padding: 50px;   
}

.d {
    background: lightblue;
    position: relative;
    height: 300px;
    width: 300px;
}

.d:before {
    box-shadow: 0 -1px 15px 1px rgba(0, 0, 0, .3);
    display: block;
    content: ' ';
    border-bottom-right-radius: 15px 100px;
    border-bottom-left-radius: 15px 100px;
    height: 50%;
    
    left: 0;
    position: absolute;
    right: 0;
    top: 0;
    z-index: -1;
}