use CGI;
use HTML::Template;

my $cgi = CGI->new; 
my $template;

print $cgi->header;

if ($cgi->param('name') && $cgi->param('color')) {
    $template = 'color2';
} else {
    $template = 'color1';
}

my $t = HTML::Template->new(filename => "$template.tmpl", associate => $cgi);
print $t->output;