.header {
  padding-bottom: 28px;
}
.header .img-youxue {
  width: 53%;
}
.header .img-youxue img {
  max-width: 100%;
}
.header .brief-intro {
  width: 45%;
  margin-left: 2%;
  margin-top: 10px;
}
.header .brief-intro p:first-child {
  color: #212121;
  font-size: 30px;
  font-weight: bold;
}
.header .brief-intro p:nth-child(2) {
  margin-top: 38px;
}
.header .brief-intro p:nth-child(n+2) {
  color: #313131;
  font-size: 18px;
  line-height: 38px;
}
.header .brief-intro .enroll-btn {
  display: inline-block;
  width: 180px;
  height: 42px;
  text-align: center;
  line-height: 42px;
  background-color: #fd4e3e;
  color: #fff;
  font-size: 16px;
  border: none;
  border-radius: 21px;
  margin-top: 56px;
}
.detail-introl {
  margin-top: 24px;
  margin-bottom: 115px;
}
.detail-introl h1,
.detail-introl h2 {
  font-weight: bold;
}
.detail-introl h1 {
  font-size: 18px;
}
.detail-introl h2 {
  font-size: 16px;
  padding-top: 26px;
}
.detail-introl p {
  padding-top: 5px;
  font-size: 14px;
  line-height: 20px;
}
@media (max-width: 768px) {
  .header {
    padding: 10px;
  }
  .header .img-youxue {
    width: 100%;
  }
  .header .brief-intro {
    width: 100%;
  }
  .header .brief-intro .enroll-btn {
    margin-top: 20px;
  }
  .header .brief-intro p:first-child {
    font-size: 24px;
  }
  .header .brief-intro p:nth-child(2) {
    margin-top: 24px;
  }
  .header .brief-intro p:nth-child(n+2) {
    font-size: 14px;
    line-height: 28px;
  }
  .detail-introl {
    padding: 10px;
  }
}
@media (min-width: 769px) and (max-width: 1200px) {
  .header {
    padding: 10px;
  }
  .header .brief-intro .enroll-btn {
    margin-top: 20px;
  }
  .header .brief-intro p:nth-child(2) {
    margin-top: 24px;
  }
  .detail-introl {
    padding: 10px;
  }
}