.yema {
    width: 520px;
    margin: 50px auto;
}
.djjz {
    width: 500px;
    height: 50px;
    background: #ddd;
    color: #777;
    line-height: 50px;
    font-size: 18px;
    text-align: center;
    margin: 50px auto;
    cursor:pointer;
}