Anyone interested in updating their css styles on the fly.  I've put this together.  It could/should be put in the preferences page I suppose.  But I am just mucking around here.  Send me change if any are made.

Enter this into roundcubemail/skins/default/mail.css

#stylechange

{

  position: absolute;

  top: 535px;

  left: 20px;

  width: 160px;

  border: 1px solid #CCCCCC;

  color: #333333;

  font-size: 11px;

  font-weight: bold;

}

Enter this into roundcubemail/program/js/common.js

var expDays = 9999; 

var standardStyle = '2';

var nameOfCookie = 'switchstyle';

var urlToCSSDirectory = 'roundcubemail/skins/default/';

var ScreenCSS_1 = 'mail.css';

var ScreenCSS_2 = 'mail_2.css';

var ScreenCSS_3 = 'mail_3.css';

var ScreenCSS_4 = 'mail_4.css';

var ScreenCSS_5 = 'mail_5.css';

//Let's you change print option CSS //

var PrintCSS_1 = 'mail_1.css';

var PrintCSS_2 = 'mail_2.css';

var PrintCSS_3 = 'mail_3.css';

var PrintCSS_4 = 'mail_4.css';

var PrintCSS_5 = 'mail_5.css';

function switchStyleOfUser(){

        var fontSize = GetCookie(nameOfCookie);

        if (fontSize == null) {

                fontSize = standardStyle;

        }

        if (fontSize == "1") { document.write('<link rel="stylesheet" type"text/css" href="' + urlToCSSDirectory + ' ' + ScreenCSS_1 + '" media="screen">'); }

        if (fontSize == "2") { document.write('<link rel="stylesheet" type"text/css" href="' + urlToCSSDirectory + ScreenCSS_2 + '" media="screen">'); }

        if (fontSize == "3") { document.write('<link rel="stylesheet" type"text/css" href="' + urlToCSSDirectory + ScreenCSS_3 + '" media="screen">'); }

        if (fontSize == "4") { document.write('<link rel="stylesheet" type"text/css" href="' + urlToCSSDirectory + ScreenCSS_4 + '" media="screen">'); }

        if (fontSize == "5") { document.write('<link rel="stylesheet" type"text/css" href="' + urlToCSSDirectory + ScreenCSS_5 + '" media="screen">'); }

        if (fontSize == "1") { document.write('<link rel="stylesheet" type"text/css" href="' + urlToCSSDirectory + PrintCSS_1 + '" media="print">'); }

        if (fontSize == "2") { document.write('<link rel="stylesheet" type"text/css" href="' + urlToCSSDirectory + PrintCSS_2 + '" media="print">'); }

        if (fontSize == "3") { document.write('<link rel="stylesheet" type"text/css" href="' + urlToCSSDirectory + PrintCSS_3 + '" media="print">'); }

        if (fontSize == "4") { document.write('<link rel="stylesheet" type"text/css" href="' + urlToCSSDirectory + PrintCSS_4 + '" media="print">'); }

        if (fontSize == "5") { document.write('<link rel="stylesheet" type"text/css" href="' + urlToCSSDirectory + PrintCSS_5 + '" media="print">'); }

        var fontSize = "";

        return fontSize;

}

var exp = new Date();

exp.setTime(exp.getTime() + (expDays*24*60*60*1000));

function getCookieVal (offset) {

        var endstr = document.cookie.indexOf (";", offset);

        if (endstr == -1)

        endstr = document.cookie.length;

        return unescape(document.cookie.substring(offset, endstr));

}

function GetCookie (name) {

        var arg = name + "=";

        var alen = arg.length;

        var clen = document.cookie.length;

        var i = 0;

        while (i < clen) {

                var j = i + alen;

                if (document.cookie.substring(i, j) == arg)

                return getCookieVal (j);

                i = document.cookie.indexOf(" ", i) + 1;

                if (i == 0) break;

        }

        return null;

}

function SetCookie (name, value) {

        var argv = SetCookie.arguments;

        var argc = SetCookie.arguments.length;

        var expires = (argc > 2) ? argv[2] : null;

        var path = (argc > 3) ? argv[3] : null;

        var domain = (argc > 4) ? argv[4] : null;

        var secure = (argc > 5) ? argv[5] : false;

        document.cookie = name + "=" + escape (value) +

        ((expires == null) ? "" : ("; expires=" + expires.toGMTString())) +

        ((path == null) ? "" : ("; path=" + path)) +

        ((domain == null) ? "" : ("; domain=" + domain)) +

        ((secure == true) ? "; secure" : "");

}

function DeleteCookie (name) {

        var exp = new Date();

        exp.setTime (exp.getTime() - 1);

        var cval = GetCookie (name);

        document.cookie = name + "=" + cval + "; expires=" + exp.toGMTString();

}

function doRefresh(){

        location.reload();

}

document.write(switchStyleOfUser());

Enter this into roundcubemail/skins/default/templates/mail.html

At the bottom just before it includes the taskbar.html

<div id="stylechange">

<input type="radio" name="rcstyl" value="1" onclick="SetCookie(nameOfCookie, this.value, exp); doRefresh();"> style 1<br>

<input type="radio" name="rcstyl" value="2" onclick="SetCookie(nameOfCookie, this.value, exp); doRefresh();"> style 2<br>

<input type="radio" name="rcstyl" value="3" onclick="SetCookie(nameOfCookie, this.value, exp); doRefresh();"> style 3<br>

<input type="radio" name="rcstyl" value="4" onclick="SetCookie(nameOfCookie, this.value, exp); doRefresh();"> style 4<br>

<input type="radio" name="rcstyl" value="5" onclick="SetCookie(nameOfCookie, this.value, exp); doRefresh();"> style 5<br>

</div>

Copy the mail.css file and modify it to your own liking naming mail_2.css mail_3.css etc etc

Done!