I am currently learning game designing in `HTML` using `Foundation Game Design with HTML5 and JavaScript By Rex van der Spuy`. In the **Positioning** chapter, there is HTML and CSS code to create a div with three empty div inside of it. Then, each of these 3 empty div have a `background-image` and it loads up the image. 

However, I do not seem to get the same result. Here is my code which is akin to what was in the book: 

```
<!doctype html>
<html>
    <title> Margins and Padding </title>
    <style>
      #stage{
        display: block;
        width: 600;
        height: 600;
        border-style: dotted;
        border-width: thin;
      }

      .content{
        width: 100;
        height: 100;
        float: left;
      }

      #image1{
        background-image: url("1.jpg");
      }
      #image2{
        background-image: url("2.jpg");
      }
      #image3{
        background-image: url("3.jpg");
      }
    </style>

  <body>
    <div id="stage">
      <div class="content" id="image1"></div>
      <div class="content" id="image2"></div>
      <div class="content" id="image3"></div>
    </div>
  </body>
</html>  

```

The images are in the same folder as the HTML page. I have tried a few things from the web but nothing worked like adding a dummy div at the end with `clear: both` and setting the `overflow` of the parent div but nothing seem to work. All I get is an empty line on the top of the screen (parent div). The book says that the images should load (and even gives a print screen) 

**Please tell me what is going wrong**