Выпадающее многоуровневое меню на css

<nav onclick="void(0);">
  <div><a href="#">Menu 1</a></div>
  <div class="dropdown-sign">Menu 2
    <div class="dropdown-content">
      <div><a href="#">Option 1</a></div>
      <div><a href="#">Option 2</a></div>
      <div><a href="#">Option 3</a></div>
      <div class="dropdown-sign">Option 4
        <div class="dropdown-content-side">
          <div>Suboption 1</div>
          <div>Suboption 2</div>
          <div>Suboption 3</div>
          <div>Suboption 4</div>
        </div>
      </div>
    </div>
  </div>
</nav>

nav {
    display: flex;
    flex-flow: row nowrap;
    justify-content: space-around;
    align-items: stretch;
    height: 2em;
    font-size: 0.9rem;
}

nav div {
    display: flex;
    flex-flow: row nowrap;
    align-items: center;
    justify-content: center;
    flex-grow: 1;
    background-color: green;
    position: relative;
    width: 100%;
    color: moccasin;
}

nav div a {
    text-decoration: none;
    color: moccasin;
    display: flex;
    flex-flow: row nowrap;
    align-items: center;
    justify-content: center;
    flex-grow: 1;
}

nav div a:hover, nav>div:hover {
    color: goldenrod;
}

.dropdown-sign::after {
    color: inherit;
    content: "▼";
    font-size: 0.6rem;
    text-indent: 0.3em;
}

.dropdown-content {
    visibility: hidden;
    z-index: 1;
    position: absolute;
    top: 2em;
}

nav>div:hover .dropdown-content {
  visibility: visible;
    background-color: darkslategray;
    display: flex;
    flex-flow: column nowrap;
    justify-content: center;
    align-items: stretch;
    width: 100%;
}

.dropdown-content>div {
    display: flex;
    flex-flow: row nowrap;
    justify-content: center;
    align-items: center;
    padding: 0.5em;
}

.dropdown-content>div:hover {
  visibility: visible;
    color: goldenrod;
    border-bottom: 0.1em solid goldenrod;
}

.dropdown-content>div>a {
    text-decoration: none;
    color: moccasin;
    display: flex;
    justify-content: center;
    align-items: center;
}

.dropdown-content>div>div:hover {
  visibility: visible;
    color: goldenrod;
    border-bottom: 0.1em solid goldenrod;
}

.dropdown-content-side {
  visibility: hidden;
    z-index: 2;
    position: absolute;
    top: 0;
    right: 100%;
    background-color: green;
    display: flex;
    flex-flow: column nowrap;
    justify-content: center;
    align-items: stretch;
    width: 100%;
}

.dropdown-content-side>div {
    display: flex;
    flex-flow: row nowrap;
    justify-content: center;
    align-items: center;
    padding: 0.5em;
}

.dropdown-content-side>div:hover {
    color: goldenrod;
    border-bottom: 0.1em solid goldenrod;
}

.dropdown-content-side>div>a {
    text-decoration: none;
    color: moccasin;
    display: flex;
    justify-content: center;
    align-items: center;
}