What is this CSS rule?

Question

In the son of suckerfish drop down menu:

http://www.htmldog.com/articles/suckerfish/dropdowns/example/

You see this rule

w\idth: 13.9em;

This can't be a typo as it appears various times in the css. What is it for?

Answer 1

This is called a CSS Hack.

Some browser will ignore the \ and treat that as a width property; other browsers will ignore the entire property.

You can see a complete list here.

Answer 2

It's a "box model hack" to workaround the incorrect box model for older IE versions.

Read more about this specific hack here: http://css-discuss.incutio.com/wiki/Box_Model_Hack

Answer 3

It's called the Modified Box Model Hack.

From the linked site:

as explained above in the section on the SBMH is hidden from IE5.x/Win because of the character escape. IE5/Mac and IE6/Win which implement the CSS box model correctly, therefore, properly get a width of 100px.

Answer 4

It likely has to do with the box model hack. Read here for more info: http://webdesign.about.com/od/css/a/aaboxmodelhack.htm