JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">

    needs to be min-heigth 100%

    <div id="sidebar">

        needs to be 40px width

    </div>
    <div id="subsidebar">

        needs to be 200px width

    </div>
    <div id="content">

        needs to be 100% width
        <div class="some-element-is-3000">
            3000px height(example)<br/>sg<br/><br/>sg<br/><br/>sg<br/><br/>sg<br/><br/>sg<br/><br/>sg<br/>
<br/>sg<br/><br/>sg<br/><br/>sg<br/><br/>sg<br/><br/>sg<br/><br/>sg<br/>
<br/>sg<br/><br/>sg<br/><br/>sg<br/><br/>sg<br/><br/>sg<br/><br/>sg<br/>
        </div>
    </div>
</div>

CSS

html,body,#container{
    width:100%;
    height:100%;
}
#container{
    display:table;
}
#sidebar,#subsidebar,#content{
    border:1px solid black;
    display:table-cell;
}
#sidebar{
    min-width:40px;
}
#subsidebar{
    min-width:200px;
}
#content{
    width:100%;
}