List Builder

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="jquery-ui.css">
    <script src="jquery.js"></script>
    <script src="jquery-ui.js"></script>

    <style>
        ul{
            width: 250px;
            cursor: pointer;
            display: inline-block;
            list-style-type:none;
            vertical-align: top;
        }
        li{
            border:1px solid gray;
            margin-bottom: 5px;
            padding:5px;
        }
        .ui-selected{
            background-color: #b81900;
        }
    </style>
</head>
<body>
<ul id="source" class="selected">
    <li>Item 1</li>
    <li>Item 2</li>
    <li>Item 3</li>
    <li>Item 4</li>
    <li>Item 5</li>
    <li>Item 6</li>
    <li>Item 7</li>
</ul>
<button id="add"> > </button>
<button id="remove"> < </button>

<ul id="dest" class="selectable">
    <li>Item 8</li>
</ul>
<script src="main.js">
</script>
</body>
</html>

$(document).ready(function (){
 $(".selected").selectable();
 $("#add").click(function (){
     $("#source").find(".ui-selected").appendTo("#dest").removeClass("ui-selected")
 })
    $("#remove").click(function (){
        $("#dest").find(".ui-selected").appendTo("#source").removeClass("ui-selected")
    })
})