.main_content {
  width: 1200px;
}
.main_list {
  width: 100%;
  display: flex;
  flex-wrap: wrap;
}
.main_item {
  width: 390px;
  margin-bottom: 60px;
  border: 1px solid #bcd4df;
  background-color: #e7f8fd;
  position: relative;
  top: 0;
  padding: 150px 55px 48px;
  box-sizing: border-box;
  transition: all 0.3s ease;
  margin-right: 15px;
}
.main_item:nth-child(3n) {
  margin-right: 0;
} 
.main_item:hover {
  top: -20px;
}
.main_item_year {
  position: absolute;
  top: 26px;
  right: 33px;
  height: 18px;
  line-height: 18px;
  font-size: 22px;
  color: #186daa;
}
.main_item_date {
  height: 16px;
  line-height: 16px;
  color: #186daa;
  margin-bottom: 20px;
}
.main_item_title {
  height: 40px;
  font-size: 18px;
  line-height: 20px;
  font-weight: bold;
  margin-bottom: 26px;
  overflow: hidden;
}
.main_item_content {
  font-size: 16px;
  height: 72px;
  line-height: 18px;
  display: -webkit-box;
  overflow: hidden;
  text-overflow: ellipsis;
  -webkit-line-clamp: 4;
  -webkit-box-orient: vertical;
  text-align: justify;
}
@media (max-width: 1220px) {
  .main_content {
    width: 800px;
  }
  .main_item {
    padding-top: 100px;
  }
  .main_item,.main_item:nth-child(3n) {
    margin-right: 20px;
  }
  .main_item:nth-child(2n) {
    margin-right: 0;
  }
  .main_item_content {
    line-height: 20px;
  }
}
@media (max-width: 819px) {
  .main_content,
  .main_item {
    width: 100%;
  }
  .main_item {
    padding-top: 70px;
    margin-bottom: 30px;
    margin-right: 0;
  }
  .main_item:nth-child(3n) {
    margin-right: 0;
  }
  .main_item_content {
    line-height: 22px;
    height: 88px;
  }
}