Add Code With Unknown License I want to download a HTML code from this website: "http://www.cssscript.com/pure-css-floating-labels-for-text-fields/", the license is "Unknown", this mean that I can edit and add the code the my website without write any License text in the edited code? In the website which I want to download the code I found this sentance:" Inspired by Matt D. Smith’s design and created by skielbasa."
No, it means you can't copy it. By default, the copyright to a work is owned by its creator, and nobody else is allowed to copy it, or create derived works, without their permission. That permission can be granted by a license. "License unknown" doesn't really tell us anything, but it certainly isn't clearly granting you permission. So you don't have permission to copy, and thus you cannot. You would have to seek permission from the copyright holder. See also If no licence is distributed with an application/source code, what license applies by default if any? (Some jurisdictions do allow for "fair use" exceptions, which allow you to copy a work without permission. You haven't said what jurisdiction you are in.)
In Germany, there is no concept that corresponds directly to public domain. You automatically hold the Urheberrecht (~ copyright) for all creative works that you make, and it can't be given up or transferred (§29 UrhG). The work only enters the Gemeinfreiheit (~public domain) 70 years after your death. You can however license Verwertungsrechte (economic usage rights). When you make creative works in the course of employment (see §43 UrhG), your employer automatically gets the Verwertungsrechte necessary in the context for the work, which is typically an exclusive right (no one else, not even you, can use the work). Your are not in an employment relationship with your school, so it has no rights to your works and cannot prevent you from publishing them on copyright grounds. When you see advice on the internet to check with your school first, that is U.S.-specific advice. Since you're still a minor (7–17), you only have limited capacity to enter contracts or legal transactions (bedingte Geschäftsfähigkeit). While you are able to make transactions involving your own means (e.g. buying something with your pocket money) or make transactions that are only to your benefit (such as accepting a gift), other transactions are schwebend unwirksam (~ pending ratification), until your parents agree. The relevant law is in §107 and §108 BGB. This is a problem with open source licenses. If you publish software under a license, this license is schwebend unwirksam. Someone might start using the software under the license. But then if your parents refuse ratification, the license would be invalid, and everyone would have to stop using your software and destroy any derivative works they made. This is a bit of a problem, especially since open source licenses are otherwise assumed to be irrevocable. So if you want to offer a license (including open source licenses), please give legal certainty to the recipients of the license and ask your parents for their consent first, possibly even in writing. Per §107 BGB, the license you offer with their consent will be valid.
You can't Under clause 7(b) of the CC-SA-BY 3.0 the licence is irrevocable providing that the licensee complies with its terms. However, ... It appears that your work is part of a Collection (as defined and under clause 4(a), the licensee has this obligation: If You create a Collection, upon notice from any Licensor You must, to the extent practicable, remove from the Collection any credit as required by Section 4(c), as requested. While you cannot have your work removed, you can have the attribution removed so that no one knows that it is your work - this would seem to meet your desire of having no association with the website. "To the extent practicable" should include anonymising you. As a bonus, if they don't do this "to the extent practicable" then they are in breach of the licence and it's automatically revoked - you can then proceed with DCMA takedown notices and/or sue for copyright breach.
While I agree that the license required for your use case isn't particularly obvious to me, the page you have linked to includes the following paragraph: Need help picking your license? Just shoot us an email at themes@getbootstrap.com and we’ll help you decide which license makes sense for your needs! So in this case, my recommendation would be to get in touch as described, that way you will know for sure that you are properly licensed.
Yes, you can. An excellent example is this very website - at the bottom of this page you will find a series of links in the footer, one of which is &quot;Terms of Service&quot;. I think you will agree that most people using the Law SE are making no money from it or paying no money to use it and yet the terms of service sets out in black and white what a user of this site can do, and what the repercussions can be if they breach the ToS, so it serves a purpose as an excellent example for your question.
If a website's TOS has restrictions against unauthorized copying and use of anything in the site, that applies to the TOS, too. Chances are, no one will do a Google search on the exact text of their TOS to find if someone has copied it; but who knows? If they paid a legal service to draft a very specific and original TOS, they may be concerned with others copying it illegally. Beyond that, their TOS is a legal document. Your TOS is a legal document. Your users sign a contract when they click and accept. If you copy and paste a TOS, and don't understand exactly what is in it, and you and your users are bound by that TOS, what kind of legal risks do you open yourself up to? A simple Google search yields https://formswift.com/terms-of-service among others. Or try one of the many services like LegalZoom.
Germany may be different, however in the United States this would be considered work-for-hire and the employer would be the rightful owner of the source code. Regardless of jurisdiction, and from a more practical point of view, you are better off not having a copy of the source code. Using it as reference or example in the future could easily turn into (unintentional) copyright infringement. If, in the future, you write code you would like to be able to freely keep and reuse in any project, make sure the owner/employer licenses it using something like the BSD, MIT, or ISC license.
You seem to assume that copyrights require paperwork such as registration. This is wrong, copyright is automatic. And it prevents the downloader from making the sort of change that you suggest. In fact, it prevents the downloader from using your template at all. The only reason the downloader can use that template is because you've granted him a specific license to ignore some copyright rules, but the default remains. And you did not grant the right to alter the template to free users.