.overlay {
    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(0, 0, 0, 0.7);
    transition: opacity 500ms;
    visibility: hidden;
    opacity: 0;
}
.overlay:target {
    visibility: visible;
    opacity: 1;
}

.popup {
    margin: 70px auto;
    padding: 20px;
    background: #e9e9e9;
    border-radius: 5px;
    border: 2px solid #aaa;
    width: 30%;
    position: relative;
    transition: all 5s ease-in-out;
}

.popup h2 {
    margin-top: 0;
    color: #333;
    font-family: Tahoma, Arial, sans-serif;
}
.popup .close {
    position: absolute;
    top: 20px;
    right: 30px;
    transition: all 200ms;
    font-size: 30px;
    font-weight: bold;
    text-decoration: none;
    color: #333;
}
.popup .close:hover {
    color: #06D85F;
}
.popup .popupcontent {
    max-height: 30%;
    overflow: auto;
    font-family: 'Arial';
    font-size: 14px;
    text-align: center;
}

.popup .popupcontent a {
    background: #fff;
    border: 2px solid #aaa;
    border-radius: 4px;
    width: 75px;
    display: inline-block;
    text-decoration: none;
}

@media screen and (max-width: 700px){
    .box{
        width: 70%;
    }
    .popup{
        width: 70%;
    }
}