I found that on many pages of the documentation of Piwik, the
href has been set to a relative URL (in some cases, a complete URL) rather than simply #section which causes it to open the link in a new tab even though the content is right there.
For example - https://piwik.org/docs/requirements/
If one clicks on any of the first 4 links, it opens a new tab with the link. The
target="_blank" also needs to be removed on most pages in my opinion.
Just a suggestion :)