Planetoid getgrav theme, header and footer menus for internal page links

Hi, I was wondering if someone can possible tell me how to produce a menu system on the front page of "getgrav.org" I really do like the idea of pages at the top menu (that one is quite easy), but it the on page links which appear at the footer than move up to the top of the page as scroll. Works really well and would be a great tutorial for people who need a mixed menu of pages and internal links .

Thanks

Really it's just using the modular on-page menu system similar to antimatter: https://github.com/getgrav/grav-theme-antimatter/blob/develop/templates/modular.html.twig#L29-L48

thanks for the reply will look in using this and see what i can work out, I presume the alternative is

is possible to build an array from the content of the page which have a selected tag or link,s in the content or I am asking a bit too much, as it would be cool to create a 2nd menu which can be dynamic from the content internal links.

Again I understand that I could use the modular pages to build the menu with a bit of coding .

Am i just thinking too far out the box especially with being a noobie !

Thanks for your help so far