var browser     = '';
var version     = '';
var entrance    = '';
var cond        = '';

if (browser == ''){
if (navigator.appName.indexOf('Microsoft') != -1)
browser = 'IE'
else if (navigator.appName.indexOf('Netscape') != -1)
browser = 'Netscape'
else browser = 'NN';
}

if (version == ''){
version= navigator.appVersion;
paren = version.indexOf('(');
whole_version = navigator.appVersion.substring(0,paren-1);
version         = parseInt(whole_version);
}

if (browser == 'IE' && version >= 4) entrance = 'yes';
if (browser == 'IE' && version < 4) entrance = 'yes';
if (browser == 'Netscape' && version >= 2.02) entrance = 'yes';
if (browser == 'Netscape' && version < 2.02) entrance = 'yes';

if (entrance=='yes'){
name0a = new Image;name0a.src = 'Top/top2a.jpg';
name0b = new Image;name0b.src = 'Top/top2b.jpg';
name1a = new Image;name1a.src = 'Top/top4a.jpg';
name1b = new Image;name1b.src = 'Top/top4b.jpg';
name2a = new Image;name2a.src = 'Top/top6a.jpg';
name2b = new Image;name2b.src = 'Top/top6b.jpg';
}


function lighten(imgName) {
if (entrance == 'yes'){
imgOn = eval(imgName + 'b.src');
document[imgName].src = imgOn;}
}
function darken(imgName) {
if (entrance == 'yes'){
imgOff = eval(imgName + 'a.src');
document[imgName].src = imgOff;}
 }