Z-index of menu with iframe

by Saksham Malhotra

HTML

<nav>
  <ul>
    <li><a href="index.html">Home</a></li>
    <li><a href="kitchendisplay.php">Calendar</a></li>
    <li>
      <a href="">Lists<span class="caret"></span></a>
      <div>
        <ul>
          <li><a href="kitchendisplay2.php">Grocery List</a></li>
          <li><a href="kitchendisplay3.php">Tasks</a></li>
          <li><a href="kitchendisplay4.php">Current Meals</a></li>
        </ul>
      </div>
    </li>
    <li><a href="NAS.php">Media</a></li>
    <li>
      <a href="">Cooking<span class="caret"></span></a>
      <div>
        <ul>
          <li><a href="meat.php">Meat Temperatures</a></li>
          <li><a href="smoker.php">Smoker</a></li>
        </ul>
      </div>
    </li>
    <li><a href="Hubitat.php">Hubitat</a></li>

  </ul>
</nav>
<iframe src="https://www.google.co.in" style="position:absolute;top:80px;left:5px;border-width:0" width="600" height="800" frameborder="0" scrolling="no"></iframe>

CSS

body {
  background-color: #EBE8E4;
  color: #222;
  font-family: "HelveticaNeue-Light", "Helvetica Neue Light", "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif;
  font-weight: 300;
  font-size: 15px;
}

nav {
  background-color: #fff;
  border: 1px solid #dedede;
  border-radius: 4px;
  box-shadow: 0 2px 2px -1px rgba(0, 0, 0, 0.055);
  color: #888;
  display: block;
  margin: 8px 22px 8px 22px;
  overflow: hidden;
  width: 610px;
}

nav ul {
  margin: 0;
  padding: 0;
}

nav ul li {
  display: inline-block;
  list-style-type: none;

  -webkit-transition: all 0.2s;
  -moz-transition: all 0.2s;
  -ms-transition: all 0.2s;
  -o-transition: all 0.2s;
  transition: all 0.2s;
  
}

nav>ul>li>a>.caret {
  border-top: 4px solid #aaa;
  border-right: 4px solid transparent;
  border-left: 4px solid transparent;
  content: "";
  display: inline-block;
  height: 0;
  width: 0;
  vertical-align: middle;

  -webkit-transition: color 0.1s linear;
  -moz-transition: color 0.1s linear;
  -o-transition: color 0.1s linear;
  transition: color 0.1s linear;
}

nav>ul>li>a {
  color: #aaa;
  display: block;
  line-height: 56px;
  padding: 0 24px;
  text-decoration: none;
}

nav>ul>li:hover {
  background-color: rgb(40, 44, 47);
}

nav>ul>li:hover>a {
  color: rgb(255, 255, 255);
}

nav>ul>li:hover>a>.caret {
  border-top-color: rgb(255, 255, 255);
}

nav>ul>li>div {
  background-color: rgb(40, 44, 47);
  border-top: 0;
  border-radius: 0 0 4px 4px;
  box-shadow: 0 2px 2px -1px rgba(0, 0, 0, 0.055);
  display: none;
  margin: 0;
  opacity: 0;
  position: absolute;
  width: 165px;
  visibility: hidden;
  z-index:1;

  -webkit-transiton: opacity 0.2s;
  -moz-transition: opacity 0.2s;
  -ms-transition: opacity 0.2s;
  -o-transition: opacity 0.2s;
  -transition: opacity 0.2s;
}

nav>ul>li:hover>div {
  display: block;
  opacity: 1;
  visibility: visible;
}

nav>ul>li>div ul>li {
  display: block;
}

nav>ul>li>div ul>li>a {
  color: #fff;
  display: block;
  padding: 12px...