Do web-builders reserve rights to websites?

I've been pondering over this one for quite a while now, and after doing some research, nothing appeared to come up. So, my questions is, when you use a website builder like webs, weebly, or other similar sites, do you reserve rights to your website? My guess is a no, as it's mostly the act of the website, but I can also see a yes, as it is your artistic creation.

As stated there may be some discrepancies if, by using a service, you've made some sort of user agreement. However in general - and in many countries regardless of agreement - the service provider owns the source code of the site components, themes, styling, javascript, etc.. while you own whatever you yourself bring to the table.

While not iron-clad, the rule of thumb is that to the author goes the copyright. Having written the code, a programmer owns the code's copyrights by default, or some company they've sold such rights to. Having produced the content, you or your sources own the copyrights to the content.

Here is the Weebly policy:
http://www.weebly.com/terms-of-service/# Consult #7. My guess is others are similar.