html - How can i show the Div/ul/List in a resposive layout below the navigation but overlaying my content?

Question

I am trying to build a responsive navigation. The idea is to build something similar to Apple's Sub Navigation (e.g. on Apple Submenu)

What i built so far is a Flexbox based navigation with an hamburger menu, animation and the responsiveness via media queries. From my perspective as a non HTML/CSS/UX/UI builder it looks good. What i am trying to figure out and implement is the following

• click on the hamburger icon
• open a ul/li list below the navigation bar
• ensure that the content is overlayed and not pushed down

I am trying now for three days and read hundreds of blogs but couldn't find any solution. Maybe someone can hel me out with my private christmas personal blog layout problem :) ?

This is my code:

$('.toggle').click(function() {
  $(this).toggleClass('active');
});

body {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Open Sans', sans-serif;
  font-weight: 300;
  font-size: 12px;
  background-color: white;
}

.wrapper {
  min-width: 375px;
  max-width: 900px;
  margin: 0 auto;
}

.header {
  padding: 5px 10px 5px 10px;
  background-color: #c6c6c6;
  color: #000;
  height: 42px;
  display: flex;
  flex-direction: row;
  align-items: center;
  justify-content: space-between;
}


.hamburger {
  display: block;
}

/* HAMBURGER ICON BEGIN */
.toggle {
  padding: 0;
  margin: 0;
  border: 0;
  background-color: transparent;
  /* display: block; */
  /* position: absolute; */
  position: relative;
  height: 2.66667em;
  width: 2.66667em;
  outline: none;
  -moz-transition: -moz-transform 0.4s cubic-bezier(0.4, 0.01, 0.165, 0.99);
  -o-transition: -o-transform 0.4s cubic-bezier(0.4, 0.01, 0.165, 0.99);
  -webkit-transition: -webkit-transform 0.4s cubic-bezier(0.4, 0.01, 0.165, 0.99);
  transition: transform 0.4s cubic-bezier(0.4, 0.01, 0.165, 0.99);
}

.gh-svg {
  position: absolute;
  left: 0;
  top: 0;
  font-size: 18px;
  fill: #000;
  -moz-transform: translateZ(0) rotate(0deg);
  -ms-transform: translateZ(0) rotate(0deg);
  -webkit-transform: translateZ(0) rotate(0deg);
  transform: translateZ(0) rotate(0deg);
  -moz-transition: -moz-transform 0.45s cubic-bezier(0.4, 0.01, 0.165, 0.99);
  -o-transition: -o-transform 0.45s cubic-bezier(0.4, 0.01, 0.165, 0.99);
  -webkit-transition: -webkit-transform 0.45s cubic-bezier(0.4, 0.01, 0.165, 0.99);
  transition: transform 0.45s cubic-bezier(0.4, 0.01, 0.165, 0.99);
}

.toggle .gh-svg-rect-top {
  -moz-transform: translate3d(0, -8px, 0);
  -webkit-transform: translate3d(0, -8px, 0);
  transform: translate3d(0, -8px, 0);
}

.toggle .gh-svg-rect-bottom {
  -moz-transform: translate3d(0, 8px, 0);
  -webkit-transform: translate3d(0, 8px, 0);
  transform: translate3d(0, 8px, 0);
}

.toggle.active .gh-svg-top {
  -moz-transform: translateZ(0) rotate(135deg);
  -ms-transform: translateZ(0) rotate(135deg);
  -webkit-transform: translateZ(0) rotate(135deg);
  transform: translateZ(0) rotate(135deg);
}

.toggle.active .gh-svg-bottom {
  -moz-transform: translateZ(0) rotate(-135deg);
  -ms-transform: translateZ(0) rotate(-135deg);
  -webkit-transform: translateZ(0) rotate(-135deg);
  transform: translateZ(0) rotate(-135deg);
}

.toggle.active .gh-svg-rect-top, .toggle.active .gh-svg-rect-bottom {
  -moz-transform: translate3d(0, 0, 0);
  -webkit-transform: translate3d(0, 0, 0);
  transform: translate3d(0, 0, 0);
}

/* HAMBURGER ICON END */

.logo {
  font-family: 'Open Sans', sans-serif;
  font-weight: 700;
  font-size: 18px;
}

.nav {
  display: flex;
  align-items: center;
  list-style-type: none;
  margin: 0;
  padding: 0;
  
  display: none;
}

.nav li {

}

.nav li a, .nav li a:visited {
  color: #000;
  text-decoration: none;
  margin-left: 10px; 
}

.nav li a:hover {
  color: #06c;
  text-decoration: none;
}


@media screen and (min-width: 480px) {
  .hamburger {
    display: none;
  } 
  
  .nav {
    display: flex;
  }
  
  body {
    background-color: #666;
  }
}

@media screen and (min-width: 900px) {
  .hamburger {
    display: none;
  } 
  
  .nav {
    display: flex;
  }
  
  body {
    background-color: #888;
  }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<link href="https://fonts.googleapis.com/css2?family=Open+Sans:wght@300;400;600;700;800&display=swap" rel="stylesheet">

<div class="wrapper">

  <div class="header">

    <!-- Page Logo #begin# -->
    <div class="logo">BLOG Y</div>
    <!-- Page Logo #end# -->

    <!-- The Navigation Items #begin# -->
    <div class="items">
      <ul class="nav">
        <li><a href="#">About</a></li>
        <li><a href="#">Products</a></li>
        <li><a href="#">Topics</a></li>
        <li><a href="#">Support</a></li>
        <li><a href="#">Contact</a></li>
      </ul>
    </div>
    <!-- The Navigation Items #end# -->

    <!-- The Hamburger Menu Icon #begin# -->
    <div class="hamburger">
      <button class="toggle">
        <svg x="0px" y="0px" width="100%" viewBox="0 0 96 96" class="gh-svg gh-svg-top" enable-background="new 0 0 96 96">
          <rect width="32" height="4" x="32" y="46" class="gh-svg-rect gh-svg-rect-top"></rect>
        </svg>
        <svg x="0px" y="0px" width="100%" viewBox="0 0 96 96" class="gh-svg gh-svg-bottom" enable-background="new 0 0 96 96">
          <rect width="32" height="4" x="32" y="46" class="gh-svg-rect gh-svg-rect-bottom"></rect>
        </svg>
      </button>
    </div>
    <!-- The Hamburger Menu Icon #end# -->

  </div>

  <div class="content">

  <p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet.</p>

  <p>Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat.</p>

  <p>Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi.</p>

  </div>
</div>

Answer 1

Greate example on: https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_responsive_navbar_dropdown

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
body {margin:0;font-family:Arial}

.topnav {
  overflow: hidden;
  background-color: #333;
}

.topnav a {
  float: left;
  display: block;
  color: #f2f2f2;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
  font-size: 17px;
}

.active {
  background-color: #4CAF50;
  color: white;
}

.topnav .icon {
  display: none;
}

.dropdown {
  float: left;
  overflow: hidden;
}

.dropdown .dropbtn {
  font-size: 17px;    
  border: none;
  outline: none;
  color: white;
  padding: 14px 16px;
  background-color: inherit;
  font-family: inherit;
  margin: 0;
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  z-index: 1;
}

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

.topnav a:hover, .dropdown:hover .dropbtn {
  background-color: #555;
  color: white;
}

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

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

@media screen and (max-width: 600px) {
  .topnav a:not(:first-child), .dropdown .dropbtn {
    display: none;
  }
  .topnav a.icon {
    float: right;
    display: block;
  }
}

@media screen and (max-width: 600px) {
  .topnav.responsive {position: relative;}
  .topnav.responsive .icon {
    position: absolute;
    right: 0;
    top: 0;
  }
  .topnav.responsive a {
    float: none;
    display: block;
    text-align: left;
  }
  .topnav.responsive .dropdown {float: none;}
  .topnav.responsive .dropdown-content {position: relative;}
  .topnav.responsive .dropdown .dropbtn {
    display: block;
    width: 100%;
    text-align: left;
  }
}
</style>
</head>
<body>

<div class="topnav" id="myTopnav">
  <a href="#home" class="active">Home</a>
  <a href="#news">News</a>
  <a href="#contact">Contact</a>
  <div class="dropdown">
    <button class="dropbtn">Dropdown 
      <i class="fa fa-caret-down"></i>
    </button>
    <div class="dropdown-content">
      <a href="#">Link 1</a>
      <a href="#">Link 2</a>
      <a href="#">Link 3</a>
    </div>
  </div> 
  <a href="#about">About</a>
  <a href="javascript:void(0);" style="font-size:15px;" class="icon" onclick="myFunction()">&#9776;</a>
</div>

<div style="padding-left:16px">
  <h2>Responsive Topnav with Dropdown</h2>
  <p>Resize the browser window to see how it works.</p>
  <p>Hover over the dropdown button to open the dropdown menu.</p>
</div>

<script>
function myFunction() {
  var x = document.getElementById("myTopnav");
  if (x.className === "topnav") {
    x.className += " responsive";
  } else {
    x.className = "topnav";
  }
}
</script>

</body>
</html>