paragraph margin-top and margin-bottom

Paragraph spacing could be adjusted in the fckeditor by uncommenting the section in the editor's style sheet that looked like the code below.

p, ul, li
{
margin-top: 50px;
margin-bottom: 50px;
}

Adding the same code to the style sheet used by the ckeditor does not work.

Is there a new way to specify the same thing? We have many stored pages that won't look right unless we can adjust the style of the ckeditor.