JSFiddle - React, Tailwind, and code Playground

HTML

<div id="mainholder">
<div id="left_window">

</div>
<div id="right_windows">
    <h1>Right window</h1>
    <div id="top_win">
        <p>dummy textdummy textdummy textdummy textdummy textdummy textdummy textdummy textdummy textdummy text</p>
    </div>
    <div id="bot_win">
        <h1>Videos</h1>
    </div>
    
</div>
<div style="clear:both;">
</div>

CSS

#mainholder{
    width:700px;
}
#left_window{
    width:450px;
    border:1px solid black;
    float:left;
    margin-right:20px;
height:300px;
}
#right_windows{
    width: 150px;
    float:left;
    border: 1px solid red;
    margin-right:10px;
    height:300px;
}
#right_windows #top_win{
    margin-top:10px;
    padding:3px;  
}
#right_windows #bot_win{
    margin-top:10px;

    padding:3px;
}