1. About the menu issue, please try to change the logo dimension. Because your logo has too much white space area on the top and bottom area. You need to remove the white space area and for the dimension maybe you can use 400px x 150px.
2. For the demo content template, in this case, you need to import the content as well, not just the style. It’s why the demo page doesn’t available on your website. But if you wont to import the content into your website, in this case, you need to import manually the demo page that you want to use. Can you tell me which demo page that you want to use? I will send the import file for you. You can send all our demo here https://jnews.io/#demo