问如何动态定位绝对div？

EN

<nav>
  <ul>
    <li>
      <a href="#">Nav menu1</a>
      <div class="menu">Content menu 1</div>
    </li>
    <li>
      <a href="#">Nav menu2</a>
      <div class="menu">Content menu 2</div>
    </li>
    <li>
      <a href="#">Nav menu3</a>
      <div class="menu">Content menu 3</div>
    </li>
    <li>
      <a href="#">Nav menu4</a>
      <div class="menu">Content menu 4</div>
    </li>
    <li>
      <a href="#">Nav menu5</a>
      <div class="menu">Content menu 5</div>
    </li>
    <li>
      <a href="#">Nav menu6</a>
      <div class="menu">Content menu 6</div>
    </li>
    <li>
      <a href="#">Nav menu7</a>
      <div class="menu">Content menu 7</div>
    </li>
    <li>
      <a href="#">Nav menu8</a>
      <div class="menu">Content menu 8</div>
    </li>
    <li>
      <a href="#">Nav menu9</a>
      <div class="menu">Content menu 9</div>
    </li>
    <li>
      <a href="#">Nav menu10</a>
      <div class="menu">Content menu 10</div>
    </li>
  </ul>
</nav>


ul {
    display: flex;
    font-size: 15px;
    height: 100%;
    border: solid 1px #ccc;
    max-width: 1200px;
    margin: 0 auto;
    padding: 24px;
    align-items: center;
    justify-content: space-between;
}

ul > li {
  display: flex;
  position: relative;
  cursor: pointer;
  padding-left: 6px;
  padding-right: 6px;
  height: 40px;
  align-items: center;
  white-space: nowrap;
  list-style: none;
}

.menu {
  display: block;
  position: absolute;
  visibility: hidden;
  color: #333;
    width: 500px;
  background: #fff;
  padding: 18px;
  min-height: 80px;
  box-shadow: 0px 2px 1px -1px rgba(0,0,0,0.2), 0px 1px 1px 0px rgba(0,0,0,0.14), 0px 1px 3px 0px rgba(0,0,0,0.12);
  opacity: 0;
  transition: all .4s ease;
  transition-delay: .3s;
  left: 0;
  top: 140%;
  z-index: 99999;
}

ul > li:hover .menu {
    display: block;
    visibility: visible;
    opacity: 1;
    top: 100%;
}