.parent_sub_menu {
  position: relative;
  display: inline-block; 
}

.sub_menu {
  position: absolute;
  width: 200px;
  top: 100%;       
  left: 0;         
  background: #fff;
  padding: 12px 16px;
  box-shadow: 0 0px 12px rgb(0 0 0 / 41%);
  border-radius: 8px;
  opacity: 0;
  pointer-events: none;
  transition: opacity .12s ease;
  display: none;   
  z-index: 999;
}
.sub_menu ul li{
    padding: 7px 0;
}

.parent_sub_menu:hover .sub_menu,
.parent_sub_menu .sub_menu:hover {
  display: block;
}

.parent_sub_menu:hover .sub_menu,
.parent_sub_menu .sub_menu:hover {
  opacity: 1;
  pointer-events: auto;
  display: block; 
}
.sub_menu { display: none; opacity: 0; pointer-events: none; transition: opacity .12s; }
.parent_sub_menu.open .sub_menu { display: block; opacity: 1; pointer-events: auto; }