.center_index_img {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    width: 800px;
    height: 726px;
    margin: auto;
}

a {
    font-size: 150%;
    text-decoration: none;
    font-family: tahoma, sans-serif;
    color: black;
}
img {
    border: none;
}