.mulu {
  background: rgba(222,231,222,0.5);
  position: fixed; 
  bottom: 10px; 
  left: 10px; 
  z-index: 999; 
  width: 328.35px;
}

details {
    padding: 10px 10px 10px 10px;
}

details > summary {
  list-style: none;
  padding: 0 30px 0 10px;
  cursor: pointer;
  box-shadow: 0 3px 0 #ced7ce;
}

details > p {
  padding: 0 60px 0 10px;
}

.never_open > summary::after {
  content: " "; 
  float: right;
}
.never_open:not([open]) > summary::after {
  content: " "; 
  float: right;
}

/* 自定义的三角 */
details > summary::after {
  content: "收起"; 
  float: right;
}
details:not([open]) > summary::after {
  content: "展开"; 
  float: right;

//style="background: rgba(222,231,222,0.5); position: fixed; bottom: 10px; left: 10px; z-index: 999; width: 328.35px;"
/* 
  background: #dee7de; 转换为三通道参数形式
  opacity: 0.5; 继承透明度
  */