// without css
// tinyMCE.init({theme:"simple",mode:"textareas",editor_selector:"mce-editor"});


//now with css support
//tinyMCE.init({theme:"advanced",mode:"textareas",editor_selector:"mce-editor",content_css:"stylesheets/application.css"});

//modified as so
tinyMCE.init({theme:"advanced",mode:"textareas",editor_selector:"mce-editor",content_css:""});