How to make an element not fixed?

Question

Im currently working on header and I made a hamburger slide using javascript. The problem is when the bar slides to right , the title <h2> stays in his place. I hope there is a way to make it slide with the bar.

function show() {
  document.getElementById('sidebar').classList.toggle("active");
}

header {
  background: #ff5f88e6;
  padding: 25px;
  overflow: hidden;
}

header h2 {
  margin-top: 0px;
  color: #fff;
  text-align: center;
}

#sidebar {
  position: absolute;
  height: 100%;
  width: 250px;
  padding: 24px 20px;
  left: -300px;
  top: 0
}

.toggle-btn {
  left: 340px;
  top: 15px;
  position: absolute;
}

.toggle-btn span {
  width: 45px;
  height: 4px;
  background: #000;
  display: block;
  margin-top: 8px;
}

#sidebar.active {
  left: 0;
  transition-duration: 500ms;
}

#sidebar ul li {
  padding: 20px 24px;
  font-size: 25px;
  border-radius: 50px;
}

<header>

  <div id="sidebar">
    <div class="toggle-btn" onclick="show()">
      <span></span>
      <span></span>
      <span></span>
    </div>
    <div class="menu">
      <ul>
        <li><a href="#">Category</a></li>
        <li><a href="#">Discusion</a></li>
        <li><a href="#">Quotes</a></li>
        <li><a href="#">Add Review</a></li>
      </ul>
    </div>


    <h2>"A Book can change the way you look"</h2>

</header>
</div>

that's what's before clicking on the hamburger what happens after I want the title to slide right so the user can read it

Answer 1

An easy option is to add a class to the header element as well when you move the menu to move the h2 element as well.

Edit: I removed the active class from the sidebar and just created a css selector to change the menu based on the parent active class. This selector #header.active #sidebar

function show() {
  document.getElementById('header').classList.toggle("active");
}

header {
  background: #ff5f88e6;
  padding: 10px;
  overflow: hidden;
  display:flex;
  justify-content:center;
  align-items: center;
}

#header.active h2{
  margin-left: 300px;
}

header h2 {
  transition: 500ms all;
  margin: 0;
  padding: 0;
  color: #fff;
  text-align: center;
}

#sidebar {
  position: absolute;
  height: 100%;
  width: 250px;
  padding: 24px 20px;
  left: -300px;
  top: 0;
  transition: 500ms all;
}

.toggle-btn {
  left: 340px;
  top: 10px;
  position: absolute;
}

.toggle-btn span {
  width: 45px;
  height: 4px;
  background: #000;
  display: block;
  margin-top: 8px;
}

#header.active #sidebar {
  left: 0;
}

#sidebar ul li {
  padding: 20px 24px;
  font-size: 25px;
  border-radius: 50px;
}

<header id="header">
  <div id="sidebar">
    <div class="toggle-btn" onclick="show()">
      <span></span>
      <span></span>
      <span></span>
    </div>
    <div class="menu">
      <ul>
        <li><a href="#">Category</a></li>
        <li><a href="#">Discusion</a></li>
        <li><a href="#">Quotes</a></li>
        <li><a href="#">Add Review</a></li>
      </ul>
    </div>    
  </div>
  <h2>"A Book can change the way you look"</h2>
</header>