CSS and Js not loading with https
So after researches, everything work now and here is my configuration :

I putted this code into my sites/default/setting.php file :

$conf['https'] = FALSE;
if (isset($_SERVER['HTTPS']) &amp;&amp; strtolower($_SERVER['HTTPS']) == 'on') {
  $base_url = 'https://www.efficient-network.eu';
}
else {
  $base_url = 'http://www.efficient-network.eu';
}
$_SERVER['HTTPS'] = 'On'; 


And needed to add a custom module to load every line in &lt;head&gt; &lt;/head&gt; with https :

function https_process_html(&amp;$vars)
{
    foreach (array('head', 'styles', 'scripts') as $replace) {
        if (!isset($vars[$replace])) {
            continue;
        }

        $vars[$replace] = preg_replace('/(src|href|@import )(url\(|=)(")http(s?):/', '$1$2$3', $vars[$replace]);
    }
}


I don't know if it's the proper method, but it works.