.materials-topic {
  color: #fff;
}
.materials-topic-wrapper {
  margin: 20px auto;
  padding: 4px 2%;
  width: 92%;
}

.content-header {
  color: #fff;
}

.materials-item {
  border-bottom: 1px solid #777;
  padding: 12px 20px;
}
.materials-item-flex {
  display: flex;
  align-items: center;
}
.materials-item-inner {
  padding: 4px 12px;
}

.material-item-playbtn {
  border: 1px solid #ccc;
  border-radius: 2px;
  padding: 0 6px;
}
.materials-item-url {
  padding: 4px 12px;
}

.materials-item-description {
  color: #aaa;
}