Copy this code and paste it in your HTML
<?
$selector = 'ul';
for($i=1;$i<11;$i++) {
if ($i % 2 != 0) {
echo "{background-color:green;width:100%;height:20px;display:block;float:left;}\n\n";
} else {
echo "{ background-color:blue;width:80%;height:20px;display:block;float:left;}\n\n";
}
}
?>