html, body {
        margin: 0;
        width: 100%;
        height: 100%;
        font-family: "yahei";
        color:#fff;
        font-size:5vw;
    }
    * {
        margin:0;
        padding: 0;
    }
    a {
      color: #000;
      text-decoration: none;
    }
    ul {
        list-style: none;
    }
    .mt-5{margin-top: 5vw;}
    .mb-5 {margin-bottom: 5vw;}
    .mt-10{margin-top: 10vw;}
    .mt-15{margin-top: 15vw;}
    .mt-20{margin-top: 20vw;}
    .mt-25{margin-top: 25vw;}
    .mt-30{margin-top: 30vw;}
    .mt-35{margin-top: 35vw;}
    .flex{display: flex;}
    .t-center {
      text-align: center;
    }
    .f-bold {
      font-weight: 600;
    }
    .a-center{justify-content: center;}
    .h-center{align-items: center;}
    .w-20{width:20vw;}
    .w-30{width:30vw;}
    .w-40{width:40vw;}
    .w-50{width:50vw;}
    .w-60{width:60vw;}
    .w-70{width:70vw;}
    .w-80{width:80vw;}
    .w-90{width:90vw;}
    .w-100{width:100vw;}
    .h-10{height:10vh;}
    .h-15{height:15vh;}
    .h-20{height:20vh;}
    .h-25{height:25vh;}
    .h-30{height:30vh;}
    .h-40{height:40vh;}
    .h-50{height:50vh;}
    .h-60{height:60vh;}
    .h-70{height:70vh;}
    .h-80{height:80vh;}
    .h-90{height:90vh;}
    .h-100{height:100vh;}
    .img-contain{object-fit: contain;max-width:100%;}
    .img-cover{object-fit: cover;}
    .pd-10{padding:10vw;}
    .flex-1{flex:1;}
    .flex-column{flex-direction: column;}
    .copy-right {
      height: 8vh;
      line-height: 8vh;
      color: #a0a0a0;
      font-size: 4vw;
    }
    .item {
      background: #e60012 url(../images/bg.png) no-repeat bottom center;
      background-size: 100vw auto;
    }
    .item1 .text {
      font-size: 6vw;
    }
    .item2 {
      background: #e60012 url(../images/bg2.png) no-repeat bottom center;
      background-size: 100vw auto;
    }
    .item2 .t-btn a{
      width: 78vw;
      background: #fff;
      color: #000;
      padding: 3vw;
      border-radius: 5vw;
      font-size: 4.2vw;
      box-shadow: #999 1px 2px 10px 0;
      display: block;
    }
    .back {
      position: fixed;
      bottom: 5vw;
      right: 5vw;
    }