JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <script language="javascript" type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
    <style>
    /* Remove this line and it works */

    #featureleft {position:relative;}

    /* End */

    #layoutdiv { text-align: left; width: 940px; }
    #featureleft { width: 580px; float: left;z-index:10; background:red; }
    #featureright { float: right; z-index:100;}
    #copypaste { background-color: #bbb; margin-bottom: 40px; padding-right: 10px; padding-left: 10px; width: 300px; height:200px; margin-left: 20px; border: solid 5px #000; }
    </style>
    
    <script language='javascript'>
    $(document).ready(function() {
        $('#copypaste').mouseenter(function(){
            
            p=$(this).position();
            // increase/move by p.left
            move=Math.round(p.left)-0;
            width=parseInt($(this).css('width'))+parseInt(move);
            margin=0-(parseInt(move)-20);
            inputs=parseInt(move)+280;
            $(this).css('width',width+'px').css('margin-left',margin+'px').css('height',$(this).height);
        });

        $('#copypaste').mouseleave(function(){
            $(this).css('width','300px');
            $(this).css('margin-left','20px');
        });
    });
</script>
</head>

<body>
    <div id="layoutdiv" class='container fakewindowcontain'>
        <div id='featurewrapper'>
            <div id='featureleft'>
                <p>Lorem ipsum dolor sit amet, ut eget et enim, nec auctor habitasse eu mattis eget odio, lacinia vivamus libero dictum, tempor nunc nec nam fringilla mauris, et class dolor curabitur ipsum. Commodo ultricies id</p>
            </div>
        
            <div id='featureright'>
                <div id='copypaste'>
                <p>Lorem ipsum dolor sit amet, ut eget et...