Adding style.css in simple mode

Hello,
I want to know, if it is possible to add a style.css to the simple mode. It seems this dos not work. When I copy the complete code from my advanced mode (where the classes list drops down) to the simple mode, all works but no classes are available.
Thanks for help

My init Code:
tinyMCE.init({
mode : "exact",
file_browser_callback: "imceImageBrowser",
init_instance_callback : "resizeEditorBox",
theme : "advanced",
convert_urls : false,
plugins : "safari,pagebreak,style,layer,table,save,advhr,advimage,advlink,emotions,iespell,insertdatetime,preview,media,searchreplace,print,contextmenu,paste,directionality,fullscreen,noneditable,visualchars,nonbreaking,xhtmlxtras,template",
theme_advanced_buttons1 : "save,|,undo,redo,|,bold,italic,underline,|,justifyleft,justifycenter,justifyright,justifyfull,|,sub,sup,|,formatselect,styleselect,",
theme_advanced_buttons2 : "cut,copy,paste,pastetext,pasteword,|,search,replace,|,bullist,numlist,|,link,unlink,anchor,image,media,charmap,hr",
theme_advanced_buttons3 : "tablecontrols,|,visualaid,|,removeformat,cleanup,code,|,preview,print,|,fullscreen",
theme_advanced_toolbar_location : "top",
theme_advanced_toolbar_align : "left",
theme_advanced_statusbar_location : "bottom",
theme_advanced_resizing : true,
extended_valid_elements : "a[name|href|target|title|onclick|class],img[style|class|src|border=0|alt|title|hspace|vspace|width|height|align|onmouseover|onmouseout|name],hr[class|width|size|noshade],font[face|size|color|style],span[class|align|style]",
template_external_list_url : "example_template_list.js",
content_css: "sites/all/themes/yaml/layouts/yaml_3col_standard/css/modules/_editor_content.css" // change this to suit your site - classes associated with divs (eg div.mystyle) will appear in the style dropdown
});