[jQuery] How to use jGrowl's "theme" option?

[Wolfram Rösler]

Hello,

does anyone have an example how to use jGrowl's "theme" option? I want
to use display error messages in red and tried the following:

$.jGrowl('My error message',{theme: 'jgError'});

with the following in my css file:

.jgError
{
  color: red;
}

but it didn't work. I am obviously doing something wrong here. Does
anyone have an example of how to do it right?

Thanks for your help
W. Rösler