When I create an HTML div element with no content, it disappears. 

When the div is populated, like this HTML, then it works right.

```
<!doctype html>
<head>
<style>
    .nav {
        width: 26%;
        display: inline;
        float: left;
        margin-left: 2%;
        margin-right: 2%;
        background-color: #FF0000;
    }
    .content {
        width: 56%;
        display: inline;
        float: left;
        margin-left: 2%;
        margin-right: 2%;
        background-color: #0000FF;
    }
</style>
</head>

<body>
    <div style="width: 600px;">
        <div class="nav"><p>nav</p></div>
        <div class="content"><p>content</p></div>
    </div>
</body>
</html>

```

I get the following (expected) output:

[![alt text](https://i.stack.imgur.com/79kEs.png)](https://i.stack.imgur.com/79kEs.png)

However, if I change the `div` element with the `class = nav` to no content:

```
<div class="nav"></div>

```

The red box disappears:

[![alt text](https://i.stack.imgur.com/wfPnh.png)](https://i.stack.imgur.com/wfPnh.png)

It's like there is no div there! How can I always have the program show the div with no content?