/*  可折叠内容  */
  .collapsible {
  background-color: rgba(128,128,128,0.2); /* #eee */
  cursor: pointer;
  padding: 18px;
  width: 100%;
  border: none;
  text-align: left;
  outline: none;
  font-size: 15px;
}
  
/* 图标+和- */
.collapsible:after {
  content: '\002B';
  color: black;
  font-weight: bold;
  float: right;
  margin-left: 5px;
}

.active:after {
  content: "\2212";
}
  
/* 设置可折叠内容的样式。 注意:默认隐藏 */
.content {
  padding: 0 18px;
  display: none;
  overflow: hidden;
}