Calibre Content Server: change summary.html (downloadlinks)

Hi all,

I want to change the summary.html of the calibre Content Server, wich displays the list of books.

I replaced the "get" Button with
This displays:

I would like to have the downloadlinks like this:

How can I change the html page to get this?

I found this Site:
https://manual.calibre-ebook.com/template_lang.html
but a simple {fmt:uppercase()} does not work.

Looks like I got something wrong.