lachang-wxapp/ThorUI/components/dropdown-list/dropdown-list.wxss

.tui-dropdown-list{
   position: relative;
}

.tui-dropdown-view {
  width: 100%;
  overflow: hidden;
  position: absolute;
  z-index: 9999;
  left: 0;
  /* opacity: 0; */
  visibility: hidden;
  transition: all 0.2s ease-in-out;
 
}

.tui-dropdownlist-show {
  /* opacity: 1; */
  visibility: visible;
}