JSFiddle - React, Tailwind, and code Playground

HTML

<div id="conteneur">

        <div id="header">
            <p>header</p>
            
        </div><!--fin header-->
        
        <div id="main_content">
            
            <div id="conteneur_centre_actu">
              
                 ...

CSS

body {
    margin: 0;
}

#conteneur
{
    width: 150px;
    position: relative;
    margin: auto;
}
#conteneur > * {
    transform: scale(0.4);
    -webkit-transform:scale(0.4);
    -moz-transform:scale(0.4);
    transform-origin: 0 0;    
    -webkit-transform-origin: 0 0;    
    -moz-transform-origin: 0 0;    
}
#header
{
    position:fixed;
    top:0;
    z-index:3;
    width:150px;
    height:81px;
    background-color:#ccc;
    padding-bottom:8px;
}

#main_content
{
    padding-left:78px;
}

#conteneur_centre_actu
{
    padding-top:116px;
}

.clear
{
   clear:both;
}