One Page Navigation

Hi,

I’ve made a onepage template with extra normal pages. I want to add “#” to all navigation items to scroll to the chosen section but only on the onepage template. So the link should look like https://www.myurl.com/#section. I made by adding custom links with the # in the menu backend. But when I’m on a page template like https://www.myurl.com/portfolio the links should go back to https://www.myurl.com/#section and not to https://www.myurl.com/portfolio/#section.

I hope you know what i mean. How can i achieve this without hardcoding or hardcoding the url in the backend.