html,
body {
  padding: 0;
  margin: 0;
  overflow-x: hidden;
}
@keyframes circle {
  0% {
    opacity: 0.6;
    width: 100%;
    height: 100%;
  }
  25% {
    opacity: 0.4;
    width: 115%;
    height: 115%;
  }
  50% {
    opacity: 0.2;
    width: 130%;
    height: 130%;
  }
  75% {
    opacity: 0.1;
    width: 145%;
    height: 145%;
  }
  100% {
    opacity: 0;
    width: 160%;
    height: 160%;
  }
}
.pages_index {
  img {
    display: block;
  }
  a {
    text-decoration: none;
  }
  ul,
  li {
    list-style: none;
  }
  .w {
    max-width: 1440px;
    margin: 0 auto;
    margin-top: -138px;
    position: relative;
    z-index: 2;
  }
  .w2 {
    max-width: 1024px;
    margin: 0 auto;
  }
  .banner {
    position: relative;
    .codechina {
      position: absolute;
      width: 8.2%;
      height: 4.2%;
      top: 2.8%;
      left: 11.6%;
    }
    .help {
      position: absolute;
      width: 10%;
      height: 4.2%;
      top: 2.8%;
      left: 23%;
    }
  }
  .title {
    padding: 0 270px;
    box-sizing: border-box;
    background: url(../img/title_l.png) left no-repeat,
      url(../img/title_r.png) right no-repeat;
    width: max-content;
    margin: 80px auto;
    font-size: 40px;
    font-weight: 500;
    margin-top: 120px;
  }
  p {
    font-size: 25px;
    color: #172853;
    text-align: center;
    margin-bottom: 60px;
  }
  .tab {
    border: 2px solid #4e5595;
    border-radius: 8px;
    width: 650px;
    height: 64px;
    margin: 0 auto;
    line-height: 64px;
    display: flex;
    justify-content: space-between;
    .item {
      color: #172853;
      font-size: 25px;
      width: 50%;
      text-align: center;
      height: 100%;
      cursor: pointer;
      &.active {
        background: #4e5595;
        color: #fff;
      }
    }
  }
  h3 {
    text-align: center;
    font-size: 30px;
    color: #172853;
    margin: 100px 0;
  }
  .project_list {
    display: flex;
    justify-content: space-between;
    .item {
      display: flex;
      img {
        width: 200px;
        height: 272px;
        border-radius: 8px;
      }
      ul {
        flex: 1;
        padding: 0 32px;
        margin: 0;
        li {
          font-size: 25px;
          & + li {
            margin-top: 33px;
          }
        }
        .bookname {
          font-size: 30px;
          font-weight: 500;
          color: #172853;
        }
        a,
        span {
          margin-left: 24px;
        }
        a {
          color: #409eff;
          text-decoration: underline;
        }
        .desc {
          font-size: 16px;
          color: #4c4c4c;
          padding: 18px 22px;
          background: rgba(251, 239, 216, 0.5);
          border-radius: 8px;
        }
      }
    }
  }
  .steps {
    margin-top: 100px;
    .step_item {
      border-left: 3px solid #4e5595;
      position: relative;
      padding-left: 70px;
      color: #172853;
      padding-bottom: 100px;
      &.hidden {
        display: none;
      }
      &:last-child {
        border: none;
      }
      &::before,
      &::after {
        display: block;
        content: "";
        height: 1px;
      }
      img {
        border: 2px solid #409eff;
        border-radius: 8px;
        margin-top: 50px;
      }
      .index {
        position: absolute;
        width: 64px;
        height: 64px;
        line-height: 64px;
        text-align: center;
        font-size: 30px;
        color: #fff;
        top: 0px;
        left: -32px;
        background: #4e5595;
        border-radius: 50%;
      }
      h4 {
        font-size: 25px;
        margin: 14px 0;
      }
      p {
        font-size: 20px;
        text-align: left;
        margin: 40px 0;
      }
      code {
        display: block;
        color: #fff;
        background: #3d3d3d;
        font-size: 20px;
        position: relative;
        border-radius: 8px;
        border: 1px solid #3d3d3d;
        overflow: hidden;
        padding: 48px 20px 20px;
        line-height: 36px;
        &::before {
          position: absolute;
          content: "";
          width: 100%;
          height: 28px;
          background: #c4c4c4;
          top: 0;
          left: 0;
        }
      }
    }
  }
  .visit {
    width: 156px;
    margin: 30px auto;
    position: relative;
    img {
      width: 156px;
      height: 156px;
      border-radius: 50%;
      cursor: pointer;
      position: relative;
      z-index: 9;
    }
    .circle {
      width: 100%;
      height: 100%;
      border-radius: 50%;
      border: 5px solid #4e5595;
      box-sizing: border-box;
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      -o-transform: translate(-50%, -50%);
      -ms-transform: translate(-50%, -50%);
      -moz-transform: translate(-50%, -50%);
      -webkit-transform: translate(-50%, -50%);
      animation: circle 4s linear infinite;
      &.circle2 {
        animation-delay: 1.3s;
      }
      &.circle3 {
        animation-delay: 2.5s;
      }
    }
  }
  .buttons {
    display: flex;
    justify-content: space-between;
    margin: 100px auto 200px;
    .btn {
      width: 288px;
      height: 64px;
      line-height: 64px;
      text-align: center;
      font-size: 25px;
      color: #172853;
      border: 2px solid #4e5595;
      border-radius: 8px;
      display: block;
      box-sizing: border-box;
      cursor: pointer;
      font-weight: 500;
      &.active {
        border: none;
        background: linear-gradient(90deg, #78568c 0%, #4e5595 100%);
        color: #fff;
      }
    }
  }
  .footer {
    width: 100%;
    text-align: center;
    color: #fff;
    font-size: 20px;
    height: 102px;
    line-height: 102px;
    background: #4e5595;
  }
}