Floating navigation buttons?

Hello,

I'm trying to add two floating navigation buttons to the magazine -- specifically to be used when the articles are long, so that the readers can click on buttons to either take them back to the TOC or to the top of the article again. 

I know that I could create an Overlay master layer to create a fixed navigational menu for all verticals -- but this is overkill, I think, as it's only really two buttons that I need to add. 

Is there a way to do this?

(Assuming there is): Is there a way to create dynamic links on these, where it'll understand to link to the top of the current vertical (in the case of the "Back to Top" button) regardless of what the Object ID of the top object is?

Thanks!