.wrapper {
  display: flex;
  align-items: flex-start;
  height: auto; /* or 100% if needed */
}

.sticky-div {
  position: -webkit-sticky;
  position: fixed;
  top: 100;
  z-index: 999;
  align-self: flex-start; /* very important inside flex */
}
#sticky-div { top: 80px; }
body.admin-bar #sticky-div { top: calc(80px + 32px); }



.left-sidebar #left-sidebar .inside-left-sidebar {
    height: 100%;
}
.left-sidebar #left-sidebar .inside-left-sidebar .widget_nav_menu {
    position: -webkit-sticky;
    position: sticky;
    top: 50px;
}