funda-ui/MultilevelDropdownMenu/index.css

React components using pure Bootstrap 5+ which does not contain any external style and script libraries.

/* ======================================================
    <!-- Multi-level Dropdown Menu -->
/* ====================================================== */
.navbar-nav a {
  position: relative;
  /* required */
  display: inline-flex;
  align-items: center;
}
.navbar-nav .arrow {
  transition: 0.1s ease-in-out;
  display: inline-block;
  text-align: center;
  position: absolute;
  right: -1em;
  top: 50%;
  transform: translateY(-50%) rotate(0deg);
}
.navbar-nav li {
  position: relative;
}
.navbar-nav li i {
  font-style: normal;
}
.navbar-nav li > a.active > .arrow {
  transform: translateY(-50%) rotate(90deg);
}
.navbar-nav > li ul {
  transition: max-height 0.25s ease;
  overflow: hidden;
  position: relative;
}
.navbar-nav > li:not(.active) ul {
  max-height: 0;
}
.navbar-nav > li ul ul {
  margin-top: auto;
}