Redimensionar Tiny MCE

Estoy creando un sistema de administración de contenido personalizado con un editor de texto enriquecido. Estoy usando un pequeño MCE pero no puedo ajustar el área de texto en mi div de contenido. tengo un <div></div> eso es 680px. Quiero que Tiny MCE encaje en el <div></div> adecuadamente. Sin embargo, sigue desbordándose. ¿Cómo puedo configurar el área de texto para que se ajuste a un ancho de 680 px? Gracias Una muestra de mi código está abajo

<?php
require 'janta_class.php';
$jantaObj = new janta_class();
if (!isset($_GET['pgid']) || empty($_GET['pgid'])) {
    $page_id = 1;
} else {
    $page_id = $_GET['pgid'];
}
if (isset($page_id) && !empty($page_id)) {
    $allowedTags = '<p><strong><em><u><h1><h2><h3><h4><h5><h6><img>';
    $allowedTags.='<li><ol><ul><span><div><br><ins><del>';

    //you might want to escape some literals here
    $page_data = $jantaObj->get_page($page_id);
    $page_content = $page_data['page_content'];
    $page_title = $page_data['page_title'];

    $page_content = strip_tags(stripslashes($page_content), $allowedTags);
}
?>

<!-- TinyMCE -->
<script type="text/javascript" src="./editor/jscripts/tiny_mce/tiny_mce.js"></script>
<script language="javascript" type="text/javascript">
    tinyMCE.init({
        theme : "advanced",
        mode: "exact",
        elements : "rteditor",
        plugins : "autolink,lists,pagebreak,style,layer,table,save,advhr,advimage,advlink,emotions,iespell,inlinepopups,insertdatetime,preview,media,searchreplace,print,contextmenu,paste,directionality,fullscreen,noneditable,visualchars,nonbreaking,xhtmlxtras,template,wordcount,advlist,autosave,visualblocks",

        // Theme options
        theme_advanced_buttons1 : "save,newdocument,|,bold,italic,underline,strikethrough,|,justifyleft,justifycenter,justifyright,justifyfull,styleselect,formatselect,fontselect,fontsizeselect",
        theme_advanced_buttons2 : "cut,copy,paste,pastetext,pasteword,|,search,replace,|,bullist,numlist,|,outdent,indent,blockquote,|,undo,redo,|,link,unlink,anchor,image,cleanup,help,code,|,insertdate,inserttime,preview,|,forecolor,backcolor",
        theme_advanced_buttons3 : "tablecontrols,|,hr,removeformat,visualaid,|,sub,sup,|,charmap,emotions,iespell,media,advhr,|,print,|,ltr,rtl,|,fullscreen",
        theme_advanced_buttons4 : "insertlayer,moveforward,movebackward,absolute,|,styleprops,|,cite,abbr,acronym,del,ins,attribs,|,visualchars,nonbreaking,template,pagebreak,restoredraft,visualblocks",
        theme_advanced_toolbar_location : "top",
        theme_advanced_toolbar_align : "left",
        theme_advanced_statusbar_location : "bottom",
        theme_advanced_resizing : true,

        // Example content CSS (should be your site CSS)
        content_css : "css/content.css",

        // Drop lists for link/image/media/template dialogs
        template_external_list_url : "lists/template_list.js",
        external_link_list_url : "lists/link_list.js",
        external_image_list_url : "lists/image_list.js",
        media_external_list_url : "lists/media_list.js",

        // Style formats
        style_formats : [
            {title : 'Bold text', inline : 'b'},
            {title : 'Red text', inline : 'span', styles : {color : '#ff0000'}},
            {title : 'Red header', block : 'h1', styles : {color : '#ff0000'}},
            {title : 'Example 1', inline : 'span', classes : 'example1'},
            {title : 'Example 2', inline : 'span', classes : 'example2'},
            {title : 'Table styles'},
            {title : 'Table row 1', selector : 'tr', classes : 'tablerow1'}
        ],

        // Replace values for the template plugin
        template_replace_values : {
            username : "Some User",
            staffid : "991234"
        },  
        height:"350px",
        width:"600px"
    });

</script>

<?php //echo $sHeader;   ?>
<form method="post" action="">
    <textarea id="rteditor" name="rteditor" rows="15" cols="80"><?php echo $page_content; ?></textarea>
    <br />
    <input type="submit" name="save" value="Submit" />
    <input type="reset" name="reset" value="Reset" />
</form>