Is it possible to obfuscate web design?

I've run into a pretty irritating problem that I'm sure others have faced. I just don't know what to do to try and prevent it from happening again (or if it's even possible).

I purchased an eCommerce website from flippa some time back. After purchasing, I updated the design and styles to make it look better. The improvement made a big difference to the underlying sales.

Some time thereafter (about 3 months), on a whim, I was browsing flippa when I saw my own website for sale but as a different URL/domain. In essence, the previous owner of the site saw that I had improved so ripped everything and just changed the main logo and contact details.

This really infuriated me as I had put a lot of effort into the venture. I gave up soon after as it really left me demoralised.

I now want to get into a similar venture, but am worried that the same thing will happen again. I understand obfuscation can deter users from just stealing my design template and CSS - but is there anything I can really do about preserving it's authenticity?

Thanks in advance!