The Foundry NavBar stack by @Elixir can include the Site Title or Custom text in it. It doesn’t have the ability to also include the Slogan below the Site Title. That would be quite a bit of text to keep in the actual NarBar, and probably wouldn’t work very well.
I don’t quite follow what you’re trying to do. Perhaps a screenshot or two would help us.
I just created the Title and slogan and saved them as a JPG, then used Foundry’s Mega Menu stack to create the menu. There’s an option there for you to drop in your own logo.
Thinking about it, you can also do the same with the standard Nav Bar stack. Just removing the Branding option, and use either the Rapidweaver site logo or Custom settings.
This could probably be done. Before I outline how you could do it, I’d like to second the recommendation to use a graphic.
They way you’re showing it, it’s more like a logo than a title and slogan. You’ll be able to get the fonts sized properly, especially if you’re going to have the slogan the same width of the title, if it’s done as a graphic. This can be tricky across different browsers and operating systems just using fonts and font sizing. If you are not going to be that particular about how it looks and not care if it varies for different users, then I’ll layout how you could do it.