Can www-data control root files on Ubuntu web servers?

I have read about a bazillion posts about how to set up web server ownership, directory, and file permissions. I have heard use root. Don't use root, use www-data. Don't use that, use a different user for each website. Yada, yada, yada. I decided to use root instead of www-data. I know the risks. I limit them by only allowing shell access from my IP and I have a password that would take a long time to break. I do more things but that isn't the question here. I want to show you my present tree structure. All of my hosted domains use a similar format. I'll ask a question in just a moment, but take a look:

├── [drwxr-xr-x www-data www-data]  www.website.com
│   ├── [drwxr-xr-x root     root    ]  css
│   │   ├── [drwxr-xr-x root     root    ]  font

Everything under the domain is at root ownership. What puzzles me is the www-data ownership of the folder. Questions: Can the domain line permissions allow someone to override the root ownership of files below that line? Should the domain line be set to root root?