... 

my $ele = $tree->look_down(_tag=> 'div',id=>'right');
       $ele->delete_content();
    
    my $i=0;
    
    while ($i < $right_panel) {
#element friendly node
        $ele->push_content(['strong'], "$matrix_title[$i]",['p'],"$matrix_summary[$i]",['br'],['br'],['a', {href=>"art.cgi?art=$matrix_id[$i]"}, "Read on ... ", ],['br'],['hr'],['br']);
                
    $i++;
    
    }
...

print $cgi->header(); 
print $tree->as_HTML();