JSFiddle - React, Tailwind, and code Playground

HTML

<div class='a'></div>
<div class='b'></div>

CSS

body {
    position: relative;
}
.a {
    position: absolute;
    left: 100px;
    top: 100px;
    width: 100px;
    height: 100px;
    background: #777;
}
.b {
    position: absolute;
    display: none;
    background: red;
}

JavaScript

$(function() {
    $('.a').live('mouseover mouseout', function(e) {
        switch (e.type) {
            case 'mouseover': {
                $('.b').offset({'left': $(this).offset().left, 
                                'top': $(this).offset().top})
                       .width($(this).outerWidth())
                       .height($(this).outerHeight())
                       .show();
                break;
            }        
            case 'mouseout': {
                $('.b').hide();
                break;
            }         
        }
    });
});