Static block link cuts part of the url

Question

I have a static block in which content I have this code: <a href="/de/sale">something</a> The url of the project is dns/my_installation/..., so my point is that when I click on the block link it will direct me to dns/my_installation/de/sale, but instead it gives me error 404 and the url of the page looks like this: dns/de/sale, so basically the /my_installation/ part is cut off.

Any idea why would that happen?