JSFiddle - React, Tailwind, and code Playground

HTML

<div id="header-wrap">
    Your menu<br/>
    Link1 Link2 Link3
</div>
<div id="container">
    1 A lot of TEXT !!!<br/>
    2 A lot of TEXT !!!<br/>
    3 A lot of TEXT !!!<br/>
    4 A lot of TEXT !!!<br/>
    5 A lot of TEXT !!!<br/>
    6 A lot of TEXT !!!<br/>
    7 A lot of TEXT !!!<br/>
    8 A lot of TEXT !!!<br/>
    9 A lot of TEXT !!!<br/>
    10 A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
    A lot of TEXT !!!<br/>
</div>

CSS

#header-wrap {
    background: #eeeeff;
    position: fixed;
    width: 100%;
    height: 50px;
    top: 0;
    z-index: 1;
}
#container{ 
    margin-top: 50px;
}