function zoom_plus()
{
    var result = document.getElementsByTagName("body");
    var body = result[0];
    var cls = body.className;    
    var n = parseInt(cls.substring(1, 3));
    n = 1 + n;

    if (n > 3) n = 3;

    body.className = "c" + n;
    
    windows_image_improver();
}

function zoom_minus()
{
    var result = document.getElementsByTagName("body");
    var body = result[0];
    var cls = body.className;    
    var n = parseInt(cls.substring(1, 3));
    n = n - 1;

    if (n < -3) n = -3;

    body.className = "c" + n;

    windows_image_improver();
}