Hi Julien, while we can help with minor CSS changes, but depending exactly what you have in mind, it may be more complex. Could you show me an example or describe in more detail what you’re looking for in terms of the layout?
Also just a heads-up that since your site has a Business plan, you’re entitled to live-chat and email support, accessible here:
https://wordpress.com/help/contact
You’re welcome to still post in these forums, but those other support avenues may be faster, and you’ll always get a staff reply.