Tremont | Float PNG logo center over page

Site URL: http://carlmindling.com

I have a PNG logo I’d like to float over my background image, essentially replacing the Page Overlay Typography in Tremont.
(On my site, the text Exceptional experiences.)

Is there a way to move the Site Logo from Nav and place it centered, full width, over the site?

Or, how can I upload the PNG and float it centered on my home page?

Thank you!