JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wide-container"> 
    <div class="container"> 
        <div class="left"> 
             fiks content 
        </div> 
        <div class="fluid"> 
             muutuva laiusega content 
        </div> 
    </div> 
</div>

CSS

.wide-container {
    width:100%;
    display:block;
    background-color:#f5f5f5;
}

.container {
    width: 600px;
    margin: 0 auto;
    background-color: #eee;
    position:relative;
}

.left {
    width: 200px;
    background-color: blue;
    float:left;
}

.fluid {
    width: auto;
    background-color: green;
    margin-left: 200px;
}