.material-quality {
  padding: 30px 0;
}

.material-quality .info{
    margin-bottom: 30px;
  text-align: center;
}

.material-quality .item:not(:last-child) {
  margin-bottom: 30px;
}

.material-quality .item-title {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  margin-bottom: 20px;
}

.material-quality .title {
  flex-shrink: 0;
  text-align: left;
  margin-right: 15px;
}

.material-quality .line {
  flex: 1;
  height: 2px;
  background: #333;
  margin-bottom: 2px;
  opacity: .8;
}

.material-quality .item-title span {
  line-height: 1;
  flex-shrink: 0;
  margin-left: 10px;
  font-family: "OPPOSans-M";
  display: flex;
  align-items: center;
}

.material-quality .arrow-part {
    cursor: pointer;
}

.material-quality .arrow {
  flex-shrink: 0;
  width: 15px;
  height: 14px;
  position: relative;
  margin-left: 10px;
}

.material-quality .arrow::before,
.material-quality .arrow::after {
  content: '';
  position: absolute;
  background: #333;
}

.material-quality .arrow::before {
  top: 50%;
  left: 0;
  transform: translateY(-50%);
  width: 100%;
  height: 2px;
}

.material-quality .arrow::after {
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 2px;
  height: 100%;
  transition: height .3s;
}

.material-quality .item.active .arrow::after {
  height: 0;
}

.material-quality .item-info {
  overflow: hidden;
}

.material-quality .row {
  margin-left: -5px;
  nav-left: -5px;
  margin-bottom: -30px;
}

.material-quality .row>div {
  padding: 0 5px;
  margin-bottom: 30px;
  text-align: center;
}

.material-quality .item img {
  height: auto;
  aspect-ratio: 1 / 1;
}

.material-quality .tit {
  font-size: 12px;
  margin-top: 10px;
  text-align: left;
  font-family: "OPPOSans-M";
}

@media (min-width: 768px) {
  .material-quality .row {
    margin-left: -15px;
    margin-right: -15px;
  }

  .material-quality .row>div {
    padding: 0 15px;
  }

  .material-quality .tit {
    font-size: 16px;
  }
}

@media (min-width: 1200px) {
  .material-quality {
    padding: 60px 0;
  }
  
  .material-quality .info{
   margin-bottom: 60px;
}

  .material-quality .item:not(:last-child) {
    margin-bottom: 76px;
  }

  .material-quality .item-title {
    margin-bottom: 40px;
  }

  .material-quality .title {
    min-width: 260px;
  }

  .material-quality .item-title span {
    font-size: 18px;
  }

  .material-quality .arrow {
    margin-left: 20px;
  }

  .material-quality .row {
    margin-left: -16px;
    margin-right: -16px;
  }

  .material-quality .row>div {
    flex: 0 0 20%;
    max-width: 20%;
    padding: 0 16px;
  }

  .material-quality .tit {
    margin-top: 25px;
    font-size: 18px;
  }
}

@media (min-width: 1440px) {
  .material-quality {
    padding: 81px 0 110px;
  }
  
  .material-quality .info{
   margin-bottom: 80px;
}

  .material-quality .item-title {
    margin-bottom: 58px;
  }
}

@media (max-width: 540px) {
  .material-quality .title {
    font-size: 20px;
  }
}