dupre,
<!DOCTYPE html>
<html>
<head>
<style>
body {
font-family: "Lato", sans-serif;
position: relative;
height: 1700px;
transition: all 0.3s;
}
.sidenav {
height: 100%;
width: 0;
position: fixed;
z-index: 1;
top: 0;
left: 0;
background-color: #111;
overflow-x: hidden;
transition: 0.5s;
padding-top: 60px;
}
.sidenav a {
padding: 8px 8px 8px 32px;
text-decoration: none;
font-size: 25px;
color: #818181;
display: block;
transition: 0.3s;
}
.sidenav a:hover, .offcanvas a:focus{
color: #f1f1f1;
}
.sidenav .closebtn {
position: absolute;
top: 0;
right: 25px;
font-size: 36px;
margin-left: 50px;
}
#main {
position: fixed;
left: 0px;
transition: left .5s;
padding: 4px 2px;
width: 36px;
height: 36px;
background-color: #000000;
text-align: center;
margin-left: 8px;
line-height: 36px;
}
@media screen and (max-height: 450px) {
.sidenav {padding-top: 15px;}
.sidenav a {font-size: 18px;}
}
body.open{
margin-left: 250px;
}
body.open .sidenav{
width: 250px
}
body.open #main{
left:250px;
}
.openclosebtn{
font-size:30px;cursor:pointer;
color: #FFFFFF;
}
h1{
margin: 0 auto;
text-align: center;
}
</style>
</head>
<body>
<div id="mySidenav" class="sidenav">
<a href="#" class="closebtn" >×</a>
<a href="#">About</a>
<a href="#">Services</a>
<a href="#">Clients</a>
<a href="#">Contact</a>
</div>
<div id="main">
<span class="openclosebtn">☰</span>
</div>
<h1>test</h1>
<script src="https://cdn.polyfill.io/v1/polyfill.js?Element.prototype.closest"></script>
<script>
window.addEventListener('DOMContentLoaded', function() {
var body = document.querySelector('body');
document.addEventListener("click", function(event){
var target = event.target;
if( target.closest(".sidenav") && !target.closest(".closebtn")) return;
else if(target.closest("#main")) {event.preventDefault();
body.classList.toggle("open")}
else body.classList.remove("open");
});
});
</script>
</body>
</html>