Custom environment variable to main assets folder
The easiest way to do this would be to just use root-relative resource URLs:

&lt;link rel="stylesheet" type="text/css" href="/assets/css/styles.css"&gt;
&lt;script type="text/javascript src="/assets/js/scripts.js"&gt;&lt;/script&gt;


The only disadvantage of that is it makes your site slightly less portable – you wouldn’t be able to run it from a subdirectory on a web server without updating all your URLs in the templates.

So a better option would be to define a custom config variable that holds the value of your site’s base URL in craft/config/general.php;

return array(
    'omitScriptNameInUrls' =&gt; true,

    'siteUrl' =&gt; array(
        'nl' =&gt; 'http://krycer.be/nl/',
        'fr' =&gt; 'http://krycer.be/fr/',
    ),

    'baseUrl' =&gt; 'http://krycer.be/',
),


And then access that config setting from your templates via craft.config:

&lt;link rel="stylesheet" type="text/css" href="{{ craft.config.baseUrl }}assets/css/styles.css"&gt;
&lt;script type="text/javascript src="{{ craft.config.baseUrl }}assets/js/scripts.js"&gt;&lt;/script&gt;


Note that there’s no reason to place that custom config variable within the environmentVariables config setting. The top level of the config array will work just fine for this.