#wrapper_fuku_2 {
    position: relative;
    width: 100%;
}

#wrapper_fuku_2:before {
    content_fuku:"";
    display: block;
    padding-top: 75%; /* 高さを幅の75%に固定 */
}
#content_fuku {
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
}