JSFiddle - React, Tailwind, and code Playground

HTML

<div class="menu">
    Menu Fixed com 250px
</div>
<div class="resto">
    Resto do conteudo (liquido)
</div>

CSS

body, html, .menu, .resto{
    height: 100%;
    color: #fff;
}

.menu{
    width: 250px; 
    float: left; 
    background-color: #f09; 
    position:blocked;
}

.resto{
    width:100%; 
    background: #f00;
}