回答.css

form {
    width: 400px;
    height: auto;
}

img {
    width: 40px;
    height: 40px;
    background-repeat: no-repeat;
    background-position: center;
    background-size: 30px 30px;
    border:1px solid;
    border-radius:20px;
    position: absolute;
    left: 680px;
    top: 350px;
}

div.background {
    width: 550px;
    height: auto;
}

div.transbox {
    width: 500px;
    height: auto;
}

#first {
    background: url("picture_checkOut.jpg");
}

#second {
    background: url("picture_ask.jpg");
}

#three {
    background: url("picture_center.jpg");
}

#four {
    background: url("picture_search.jpg");
}

#five {
    background: url("picture_first.jpg");
}