print header( -charset=>'utf-8' );
print start_html( -script => my $js,
                -style=>'/data/css/style.css',
                  -title=>'Order Project!' );
[download]

Wrong. You are setting up another lexical variable $js which is empty at this point.

You want

my $js = <<EOH;
// JavaScript here
EOH
print header( -charset=>'utf-8' );
print start_html( -script => $js,
                -style=>'/data/css/style.css',
                  -title=>'Order Project!' );
[download]

update: Try

td(
  popup_menu(
    -name => 'ordered_items',
    -multiple => 1,
    -id => 'ordered_items',
    -style => "width: 230px;"
  )
),
[download]

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}