You will need to configure Plack to serve up static files - there is a good tutorial in the Plack Advent Calendar - see Day 17: Serving static files from your application. It has a few examples.

If you reference your CSS file as "/static/funky.css" in your template, then this should work: 

use Plack::Builder;

my $app = sub { ... };

builder {
    enable "Static", path => qr!^/static!, root => '/Library/WebServer
+/Documents';
    $app;
}

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Update: minor edits

In reply to Re: CSS and PSGI by tangent
in thread CSS and PSGI by tiny_monk

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