This is a simple learning experience that quickly teaches the basics of CSS selectors. It assumes familiarity with basic HTML.

The experience has been designed to work well on both mobile and desktop devices. As a result, large "shortcut" buttons are available to input keystrokes like # and ., which are typically challenging to type on mobile devices. The only keys the player should ever have to directly tap on their device's keyboard are the lowercase alphabet and the space bar.

Supported desktop browsers:

• Firefox
• Safari
• Chrome
• Opera
• Internet Explorer 9

Supported mobile browsers:

• Mobile Safari
• Mobile Chrome

Unfortunately, support for Mobile Firefox is currently blocked by bug 763201 and bug 764817.