function show(elementname)
{
    document.getElementById(elementname).style.display='block';
}

function hide(elementname)
{
    document.getElementById('element').style.display='none';
}

var style_cookie_name = "tp_stylesheet" ;
var style_cookie_duration = 30 ;

function switch_style ( css_title )
{
    // You may use this script on your site free of charge provided
    // you do not remote this notice or the URL below. Script from
    // http://www.thesitewizard.com/javascripts/change-style-sheets.shtml
    var i, link_tag ;
    for (i = 0, link_tag = document.getElementsByTagName("link") ;
         i < link_tag.length ; i++ ) {
        if ((link_tag[i].rel.indexOf( "stylesheet" ) != -1) &&
            link_tag[i].title) {
            link_tag[i].disabled = true ;
            if (link_tag[i].title == css_title) {
                link_tag[i].disabled = false ;
            }
        }
        set_cookie( style_cookie_name, css_title,
                    style_cookie_duration );
    }
}
function set_style_from_cookie()
{
    var css_title = get_cookie( style_cookie_name );
    if (css_title.length) {
        switch_style( css_title );
    }
}
function set_cookie ( cookie_name, cookie_value,
                      lifespan_in_days, valid_domain )
{
    var domain_string = valid_domain ?
        ("; domain=" + valid_domain) : '' ;
    var new_cookie = cookie_name +
        "=" + encodeURIComponent( cookie_value ) +
        "; max-age=" + 60 * 60 *
        24 * lifespan_in_days +
        "; path=/tp/" + domain_string ;

    document.cookie = new_cookie;
}

function get_cookie ( cookie_name )
{
    var cookie_string = document.cookie ;
    if (cookie_string.length != 0) {
        var cookie_value = cookie_string.match (
            '(^|;)[\s]*' +
                cookie_name +
                '=([^;]*)' );
        if ( cookie_value ) {
            return decodeURIComponent ( cookie_value[2] );
        }
    }
    return '';
}