fix #7: Opener icon not visible in Safari

lib/Controller/CssController.php

@@ -38,6 +38,7 @@ class CssController extends Controller
     public function __construct($appName, IRequest $request, IConfig $config)
     {
         parent::__construct($appName, $request);
+
         $this->config = $config;
     }
 
@@ -50,6 +51,10 @@ class CssController extends Controller
      */
     public function stylesheet()
     {
+        $requestUri = $this->request->server['REQUEST_URI'];
+        $assetsRoot = str_replace('/index.php', '', $requestUri);
+        $assetsRoot = preg_replace('#apps/side_menu/.*#s', 'apps/side_menu', $assetsRoot);
+
         $parameters = [
             'vars' => [
                 'background-color' => $this->config->getAppValue('side_menu', 'background-color', '#333333'),
@@ -58,6 +63,7 @@ class CssController extends Controller
                 'opener' => $this->config->getAppValue('side_menu', 'opener', 'side-menu-opener'),
             ],
             'display-logo' => (bool) $this->config->getAppValue('side_menu', 'display-logo', 1),
+            'assetsRoot' => $assetsRoot,
         ];
 
         $response = new TemplateResponse('side_menu', 'css/stylesheet', $parameters, 'blank');