```js
  function openCity(evt, cityName) {
        var i, tabcontent, tablinks;
        tabcontent = document.getElementsByClassName("tabcontent");
        for (i = 0; i < tabcontent.length; i++) {
            tabcontent[i].style.display = "none";
        }
        tablinks = document.getElementsByClassName("tablinks");
        for (i = 0; i < tablinks.length; i++) {
            tablinks[i].className = tablinks[i].className.replace(" active", "");
        }
        document.getElementById(cityName).style.display = "block";
        evt.currentTarget.className += " active";
    }

    // Get the element with id="defaultOpen" and click on it
    document.getElementById("defaultOpen").click();
```

```css
               .dropbtn {
        background-color: #4CAF50;
        color: white;
        padding: 16px;
        font-size: 16px;
        border: none;
    }

    .dropdown {
        position: relative;
        display: inline-block;
    }

    .dropdown-content {
        display: none;
        position: absolute;
        background-color: #f1f1f1;
        min-width: 560px;
        box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
        z-index: 1;
    }

    .dropdown-content a {
        color: black;
        padding: 12px 16px;
        text-decoration: none;
        display: block;
    }

    .dropdown-content a:hover {background-color: #ddd}

    .dropdown:hover .dropdown-content {
        display: block;
    }

    .dropdown:hover .dropbtn {
        background-color: #3e8e41;
    }

    /* Style the tab */
    .tab {
        float: left;
        border: 1px solid #ccc;
        background-color: #f1f1f1;
        width: 30%;
        height: 300px;
    }

    /* Style the buttons inside the tab */
    .tab button {
        display: block;
        background-color: inherit;
        color: black;
        padding: 22px 16px;
        width: 100%;
        border: none;
        outline: none;
        text-align: left;
        cursor: pointer;
        transition: 0.3s;
        font-size: 17px;
    }

    /* Change background color of buttons on hover */
    .tab button:hover {
        background-color: #ddd;
    }

    /* Create an active/current "tab button" class */
    .tab button.active {
        background-color: #ccc;
    }

    /* Style the tab content */
    .tabcontent {
        float: left;
        padding: 0px 12px;
        /*border: 1px solid #ccc;*/
        width: auto;
        border-left: none;
        height: auto;
    } 

```

```html
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

          <div class="dropdown">
      <button class="dropbtn" href="index.html">Dropdown</button>
      <div class="dropdown-content">

    <div class="tab">
      <button class="tablinks" onclick="openCity(event, 'London')" id="defaultOpen">Discover</button>
      <button class="tablinks" onclick="openCity(event, 'Paris')">Paris</button>
      <button class="tablinks" onclick="openCity(event, 'india')">Paris</button>
      <button class="tablinks" onclick="openCity(event, 'Tokyo')">Tokyo</button>
    </div>

    <div id="London" class="tabcontent">
      <h3>London</h3>
      <p>London is the capital city of England.</p>
    </div>

    <div id="Paris" class="tabcontent">
      <h3>Paris</h3>
      <p>Paris is the capital of France.</p> 
    </div>

    <div id="india" class="tabcontent">
      <h3>India</h3>
      <p>Paris is the capital of France.</p> 
    </div>
    <div id="Tokyo" class="tabcontent">
      <h3>Tokyo</h3>
      <p>Tokyo is the capital of Japan.</p>
    </div>
      </div>
    </div>
```

I need to hover the drop down as well as hover the tabs inside the drop-down. All work is with custom CSS and JavaScript. I have tried a lot but not sure where is the mistake. How to achieve this task. Also, explain me in detail and if you have any alternative to this code u can share that one.

<https://codepen.io/srireddy1/pen/vdadjP>