#countdown {
    position: absolute;
    left: 50%;
    top: 50%;
    width: 100px;
    height: 100px;
    display: none;
    margin: -50px 0 0 -50px;
    border: 2px solid #cecece;
    background-color: #fefefe;
    text-align: center;
    line-height: 100px;
    font-size: 60px;
    font-family: sans-serif;
}