What does the smiley face “:)” mean in CSS?

Question

I spotted this CSS code in a project:

html, body { :)width: 640px;}

I have been around with CSS for a long time now but I never saw this \":)\"

Answer 1

It looks like a CSS hack to target IE7 and earlier browsers. While this is invalid CSS and browsers should ignore it, IE7 and earlier will parse and honor this rule. Here is an example of this hack in action:

CSS

body {
    background: url(background.png);
    :)background: url(why-you-little.png);
}

IE8 (ignores the rule)

IE7 (applies the rule)

Note that it does not have to be a smiley face; BrowserHacks mentions:

Any combination of these characters:
! $ & * ( ) = % + @ , . / ` [ ] # ~ ? : < > |
[before the property name will work on] Internet Explorer ≤ 7

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The GAH hot dog stand example is here.