JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<meta charset="utf-8" />
<link rel="stylesheet" href="float.css">
<div class="container">
    <br>
    <br>
    <br>
    <br>
    <div class="box">Hello my name is jack</div>
</div>
<div class="container">
    <br>
    <br>
    <br>
    <br>
    <div class="box">Hello my name is jack</div>
</div>

CSS

body {
    background : #f8f8f8 ;
    height : 2000px ;
    width: 100%;
    max-width:1100px;
    margin:0 auto;
    box-sizing:border-box;
    position:relative;
}

.header {
    position : fixed ;
    border-bottom : 1px solid #f1f1f1 ;
    width : 100% ;
    max-width:1100px;
    background:#ddd;
}
.header img {
    display : block ;
    margin-left : auto ;
    margin-right : auto ;
    margin-top : 50px ;
    margin-bottom : 50px ;
}