body {
    background-color: #fff;
    min-height: 500px;
}
.auto {
    margin: 0 auto;
    padding-top: 160px;
    /* min-width: 1000px;
    max-width: 1200px;
    _width: 1000px; */
    /*text-align: center;*/
}
/*banner背景图*/
.maintain-bg {
    width: 390px;
    height: 290px;
    margin: 0 auto;
    margin-bottom: 15px;
    background: url(img/upgrade_bg.png) no-repeat center;
}
.tip1,
.tip2,
.tip3 {
    margin-top: 30px;
    text-align: center;
    font-size: 36px;
    color: #a1aeb2;
}
.tip2 {
    font-size: 14px;
}
.tip3 {
    font-size: 26px;
}
.footer {
    position: absolute;
    left: 0;
    bottom: 30px;
    width: 100%;
    height: 25px;
    line-height: 25px;
    text-align: center;
    font-size: 12px;
    color: #333;
}

@media screen and (max-width: 750px) {
  .auto{
    padding-top: 90px;
  }
  .maintain-bg {
    width: 300px;
    height: 223px;
    background-size: cover;
  }
}