.container {
  position: relative;
  width: 100%;
  height: 100vh;
  background: url('https://cfept-1252341512.file.myqcloud.com/offcial/imgs/indexPage.jpg') no-repeat center / cover;
}
.container .plat {
  position: absolute;
  margin: 0 auto;
  text-align: center;
}
.container .platform_sub {
  position: relative;
  display: inline-block;
  width: 562.5px;
  cursor: pointer;
}
.container .new {
  display: none;
}
.container .platform_sub:hover .old {
  display: none;
}
.container .platform_sub:hover .new {
  display: block;
}
.container .wrap {
  width: 100%;
  height: 100%;
}
.container .wrap img {
  width: 100%;
  height: 100%;
}
.container .teacherTip {
  position: absolute;
  left: 0;
  top: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
  height: 100%;
  font-size: 32px;
  color: #FEFEFE;
}
.container .teacherTip1 {
  position: absolute;
  left: 0;
  bottom: 40px;
  width: 100%;
  height: 50px;
  line-height: 50px;
  text-align: center;
  color: #fff;
  font-size: 24px;
  font-weight: normal;
}
@media (min-width: 1200px) {
  .container .plat {
    left: calc(50% - 600px);
    top: calc(50% - 190px);
    width: 1200px;
  }
  .container .platform_r {
    margin-left: 30px;
  }
}
@media (min-width: 900px) and (max-width: 1200px) {
  .container .plat {
    left: calc(50% - 400px);
    top: calc(50% - 132px);
    width: 810px;
  }
  .container .platform_sub {
    width: 390px;
  }
  .container .platform_r {
    margin-left: 25px;
  }
}
@media (max-width: 900px) and (min-width: 540px) {
  .container .plat {
    left: calc(50% - 185px);
    top: calc(50% - 250px);
    width: 370px;
  }
  .container .platform_sub {
    width: 370px;
  }
}
@media (max-width: 900px) {
  .container .platform_r {
    margin-left: 0;
  }
  .container .teacherTip {
    font-size: 20px;
  }
  .container .teacherTip1 {
    font-size: 18px;
  }
  .container .teacherTip1 {
    bottom: 0px;
  }
}
@media (max-width: 539px) {
  .container .plat {
    left: calc(50% - 125px);
    top: calc(50% - 169px);
    width: 250px;
  }
  .container .platform_sub {
    width: 250px;
  }
  .container .platform_sub:hover .old {
    display: block;
  }
  .container .platform_sub:hover .new {
    display: none;
  }
}