Your repository should always be kebab-case: no capital letters, no underscores, no periods, nothing weird.
If it's a Java project, the repository name should also match the Maven artifactId. The
only exceptions, you are forking a project and want to make it clear your fork is not the
source repo, or you have multiple forks of repos that would otherwise have a name
collision. In those cases, prefixing with another word to indicate the upstream source is
advised.
If the repository is explicitly for a website, you can have periods if you're naming the repo with the domain name. But don't just name a repo with domain name and then use it as the main code repo for a project that happens to also have a website at that domain, if it's holding anything more than just a website, kebab-case rule wins.