Adding the Boilerplate HTML and CSS

The main boilerplate for an HTML5 file is minimal. You get a valid HTML file with a <canvas> element inside of a container centered on the page, as shown in Listing 1-1.

Listing 1-1: Boilerplate game HTML

<!DOCTYPE HTML>
<html lang="en">
<head>
  <meta charset="UTF-8"/>
<title>Alien Invasion</title>
  <link rel="stylesheet" href="base.css" type="text/css" />
</head>
<body>
  <div id='container'>
    <canvas id='game' width='320' height='480'></canvas>
  </div>
  <script src='game.js'></script>
</body>
</html>

The only external files so far are the base.css file, an external style sheet, and a nonexistent game.js file that will contain the JavaScript code for the game. Drop the HTML from Listing 1-1 into a new directory, and call it index.html.

In base.css you need two separate sections. The first is a CSS reset. CSS resets make sure all elements look the same in all browsers and any per-element styling and padding is removed. To do this, the reset sets the size of all elements to 100% (16 pixels for fonts) and removes all padding, borders, and margins. The reset used is the well-known Eric Meyer reset: http://meyerweb.com/eric/tools/css/reset/.

You can simply copy the CSS code verbatim to the top of base.css.

Next, you need to add two additional styles to the CSS file, as shown in Listing 1-2.

Listing 1-2: Base canvas and container styles

/* Center the container */ #container { padding-top:50px; margin:0 auto; width:480px; } /* Give canvas a background */ ...

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