These are safari specific css tags.

From qooxdoo.org:

Most browser support custom CSS tags, which are not (yet) part of any standard. These styles are usually prefixed with the browser name. Mozilla uses -moz-, Opera -o- and Safari/WebKit uses -webkit- as prefix.

I found more info on the following site:

http://qooxdoo.org/documentation/general/webkit_css_styles

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From: support-bounces@drupal.org [mailto:support-bounces@drupal.org] On Behalf Of tony maciejowski
Sent: Monday, June 20, 2011 9:13 PM
To: support@drupal.org
Subject: [support] drupal CSS question

Dear All,

I am trying to figure out  where -webkit-margin * 

comes from in the Genesis theme:

ul, menu, dir {

1. display: block;

2. list-style-type: disc;

3. -webkit-margin-before: 1em;

4. -webkit-margin-after: 1em;

5. -webkit-margin-start: 0px;

6. -webkit-margin-end: 0px;

7. -webkit-padding-start: 40px;

}

Did  search of everything with no luck. 

thanks

--

tony maciejowski