[jQuery] Check to see if a style exists

[David]

Hi All,

Is there way to check to see if a style class is declared within a 
document or css file related to the document? I'm building a plugin for 
our designer's internal use, with the goal of replacing the standard 
javascript dialogs with dialog boxes created with jqModal. I want to 
provide the designers with the flexibility to be able to style the 
dialog boxes to suit a site style but have a default style for the 
dialog if none is supplied.

e.g.:

if ( styles for #customConfirmDialog not declared in document/css ) {
   $("#customConfirmDialog").css({ ... });
}
$("#customConfirmDialog").show();

I'm sure I've seen this question asked on the list before but I can't 
find it and can't think of a way to search for it that won't return a 
thousand results.

Regards,

David