add last modification timestamp to app.css?v= so that browsers don't cache old versions
add last modification timestamp to app.css?v= so that browsers don't cache old versions

openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server,openfoodfacts/openfoodfacts-server