.post-div {
    width: 700px;
    max-width: 100%;
    margin-bottom: 20px;
    padding: auto;
    background-color: blueviolet;
}

.lay {
    position:fixed;
    width: 300px;
    height: 300px;
    top: 50px;
    left: 200px;
    background-color: antiquewhite;
    display: none;
}

.layicon {
    position:absolute;
    top: 20px;
    right: 20px;
    color:blueviolet;
    font-size: 20px;
    cursor: pointer;
}

.lay.active {
    display: block;
}