JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="shadowed">
    <div class="dragMe">
    </div>
        <div class="dragMe">
    </div>
</ul>

CSS

.shadowed {
    width: 256px;
    height: 64px;
    margin: 100px;
    background: #777;
}

.shadowed:before{ 
    content: "";
    width: 256px; 
    height: 64px;
    position: absolute;
    margin: 100px;
    top: 0; 
    left: 0;
    box-shadow: inset 0px 0px 10px 2px #000;
}

.dragMe {
    width: 64px;
    height: 64px;
    background: red;
}

JavaScript

$(function() {

    $( ".dragMe" ).draggable({
        
        /* try dragging the red square, then remove this line and try again. */
        helper: "clone",
        
        
        revert: "invalid",
        stack: ".dragMe"
    });
    
    $( ".shadowed" ).droppable({
    drop: function(event, ui) {
        $.ui.ddmanager.current.cancelHelperRemoval = true;
    }
}).sortable().disableSelection();   
});