<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Navigation using CSS flexbox</title>
</head>
<body>
  <div class="menu">
    <ul>
      <li><a href="#">Home</a></li>
      <li><a href="#">About</a></li>
      <li>
        <a href="#">Services +</a>
        <ul>
          <li><a href="#">Website</a></li>
          <li><a href="#">Web App</a></li>
        </ul>
      </li>
      <li><a href="#">Portfolio</a></li>
      <li><a href="#">Contact</a></li>
    </ul>
  </div>  
</body>
</html>
*
{
  margin: 0;
  padding: 4px;
  box-sizing: border-box;
  font-family: 'Poppins', sans-serif;
}

.menu
{
  background: #27ae60;
  border-radius: 6px;
}

.menu ul
{
  display: flex;
  justify-content: space-evenly;
  align-items: center;
}

.menu ul li
{
  list-style: none;
  padding: 4px;
  position: relative;
  transition: 0.5s;
  display: block;
}

.menu ul li a
{
  color: #fff;
  text-decoration: none;
  padding: 5px 10px;
}

.menu ul li a:hover
{
  
  background: #2ecc71;
  border-radius: 6px;
}

.menu ul li ul
{
  display: none;
}

.menu ul li:hover ul
{
  display: block;
  position: absolute;
  margin-top: 5px;
  background: #27ae60;
  border-radius: 6px;
  width: 100%;
  padding: 10px 2px;
  box-shadow: 0px 20px 100px 0px rgba(0, 0, 0, 0.5);
}

External CSS

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External JavaScript

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