```
$(document).ready(function() {
    $( "#box" ).resizable();
});

.container {
    width: 450px;
    height: 450px;
    background-color: #000;
}

#box {
    width: 150px;
    height: 150px;
    background-color: red;
    padding: 0.5em; 
}

<div class="container">
    <div id="box">
    </div>
</div>

```

All I see is a red box, inside a black box, cannot see the resize icon at all like in the example here:

<http://jqueryui.com/resizable/#helper>

I looked at their css file, it seems like with the class `.ui-widget-content` it works, but why?

What makes that resize icon popup in there?
Why doesn't it work? 

there:

```
<html>
<head id="html">
<title>Jquery project</title>
<script src="http://code.jquery.com/jquery-1.9.1.min.js" type="text/javascript"></script>
<script src="http://code.jquery.com/ui/1.10.3/jquery-ui.js"></script>

</head>

<div class="container">
    <div id="box">
    </div>
</div>
<style>
.container {
    width: 450px;
    height: 450px;
    background-color: #000;
}

#box {
    width: 150px;
    height: 150px;
    background-color: red;
    padding: 0.5em; 
}
</style>
<script>
$(document).ready(function() {
    $( "#box" ).resizable();
});
</script>
</html>

```