<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
<style>
* {
box-sizing: border-box;
}
body {
margin: 0;
overflow-x: hidden;
}
.parent {
max-width: 400px;
margin: 0 auto;
padding: 1rem;
position: relative;
background-color: #c0c2c2;
}
.child {
width: 100vw;
position: relative;
left: calc(-50vw + 50%);
height: 100px;
background-color: #535fcf;
}
</style>
</head>
<body>
<div class="parent">
<div class="child"></div>
</div>
</body>
</html>