ajout logo svg et optimisation du thème

custom_overlay.css

@@ -15,12 +15,12 @@
 
 #ynh-overlay-switch {
   /* FIXME : idk if this is an issue or not to have /yunohost/sso hard-coded here */
-  background-image: url("/yunohost/sso/assets/img/logo-ynh.svg");
-  border-color: #eee;
-  background-color: #eee;
+  background-image: url("/yunohost/sso/assets/themes/weblibre/img/weblibre-ynh.svg");
+  border-color: #ddd;
+  background-color: #ddd;
 }
 
 #ynh-overlay-switch:hover {
-  border-color: #ccc;
-  background-color: #ccc;
+  border-color: #ddd;
+  background-color: #ddd;
 }

custom_portal.css

@@ -6,11 +6,11 @@
 */
 
 body {
-   background: #fff;
+   background: #ddd;
 }
 
 #ynh-logo {
-  background-image: url("../../img/logo-ynh.svg");
+  background-image: url("img/weblibre-ynh.svg");
 }
 
 .login-form .form-group {