body{
 
}
/* 超小屏幕（手机，小于 768px） */
@media screen and (max-width: 767px) {
    nav{
      display: block;
    }
    .self-nav{
      display: none;
    }
    .section_5{
        height: 255px !important;
    }
    .section_5 .content{
        color: #fff;
        position: absolute;
        top: 10%;
        left: 20%;
    }
  }
  /* 小屏幕（平板，小于等于 1023px） */
  @media screen and (min-width: 768px) and (max-width: 1023px) {
    nav{
      display: none;
    }
    .self-nav{
      display: block;
    }
    .section_5 .content{
        color: #fff;
        position: absolute;
        top: 40%;
        left: 20%;
    }
  }
  /* 大屏幕（桌面显示器，大于等于 1024px） */
  @media screen and (min-width: 1024px) {
    nav{
      display: none;
    }
    .self-nav{
      display: block;
    }
    .section_5 .content{
        color: #fff;
        position: absolute;
        top: 40%;
        left: 20%;
    }
  }
  * {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: PingFangSC-Thin;
  }
  .navbar-brand{
    padding: 0;
  }
  .navbar-brand img{
    height: 100%;
  }

  ul, li{
    list-style: none;
  }
  
  .self-nav{
    position: absolute;
    top: 0;
    left: 50%;
    -webkit-transform: translateX(-50%);
    -o-transform: translateX(-50%);
    -moz-transform: translateX(-50%);
    transform: translateX(-50%);
    z-index: 111;
  }
  .self-nav ul{
    display: flex;
    justify-content: space-around;
    padding-left: 40px;
  }
  .self-nav ul li{
    line-height: 124px;
  }
  .self-nav ul li a{
    font-size: 14px;
    color: #fff;
  }
  .self-nav ul li.activity a{
    color: #ff5800;
  }
  .self-nav ul li img{
    width: 200px;
  } 
  
  .index-banner {
    height: 34.5vw;
    background: url(../img/banner_4.png) center no-repeat;
    background-size: cover;
    text-align: center;
    color: #fff;
    position: relative;
  }

  .index-banner div{
      width: 23.5vw;
      position: absolute;
      right: 17vw;
      top: 20%;
  }
  .index-banner div img{
      width: 55%;
  }
  .activity_step{
      margin-top: 150px;
  }
  .activity_step .step{
    padding-bottom: 50px;
  }
  .activity_step .step div{
      margin: auto;
      width: 209px;
      height: 142px;
  }
  .activity_step .step div img{
      width: 100%;
      height: 100%;
  }
  .activity_step .step p:nth-of-type(1){
    font-size: 24px;
    text-align: center;
    margin-top: 20px;
    font-weight: bold;
}
.activity_step .step p:nth-of-type(2){
    font-size: 15px;
    line-height: 24px;
    color: #898888;
    width: 80%;
    margin: auto;
}
.img_box img{
    width: 100%;
}
.section_4{
    padding: 50px 0;
}
.section_4 .row{
    padding: 50px 0;
}
.section_4 .text_module{
    padding: 50px 0;
}
.section_4 .text_module p:nth-of-type(1){
    font-size: 24px;
    font-weight: bold;
    width: 62%;
    margin: auto;
    padding-left: 2.5%;
}
.section_4 .text_module p:nth-of-type(2){
    font-size: 14px;
    color: #898888;
    width: 55%;
    margin: auto;
    margin-top: 30px;
}
.section_4 .img_module{
    text-align: center;
}
.section_4 .img_module img{
    width: 60%;
}
.section_5{
    height: 28.4vw;
    background: url('../img/function_5.png') no-repeat;
    background-size: 100% 100%;
    position: relative;
}
.section_5 .content p:nth-of-type(1){
    font-size: 24px;
    font-weight: bold;
    margin-bottom: 30px;
}
.section_5 .content p:nth-of-type(2){
    font-size: 14px;
    width: 45%;
}
.section-7 {
    background-color: #E6E6E6;
    color: #8B8B8B;
  }
  .section-7 p {
    margin: 10px 0;
  }