JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">

    <div id="menu">
    </div>



        <div id="column1" class="column_n">1
        </div>

        <div id="column2" class="column_n">2
        </div>

        <div id="column2" class="column_n">3
        </div>
        
        <div id="column2" class="column_n">4
        </div>
        
   
        <div id="column2" class="column_n">5
        </div>
        
        <div id="column2" class="column_n">6
        </div>
        
        <div id="column2" class="column_n">7
        </div>
</div>

CSS

body {
    margin: 0;
    padding: 0;
    border: 0;
    font-family: Verdana;
    font-size: 20px;
overflow: hidden;
}

#menu{width:1280px;height:30px;position:relative;float:left;background:yellow;}

#container{width:aut;height:auto;background:green;position:absolute;}

.column_n {
    clear: none 
    width: 200px;
    height:800px;
    float: left;
    position:relative;
    background:red;
    border-left: 1px dashed pink; 
}