Redesign archive

[aknierim]

Proof-of-concept of a redesigned and tidier archive download section using a grid of cards:

Some further notes:

• We also may want to think about whether we want to give the "current" and "latest" archives a similar makeover.
• We can also add buttons to the cards where the users can choose from .zip or .tar.gz file format downloads, something @SepplL suggested

[SepplL]

Added the zips now to evaluate, if we actually want that in the future. Easy to remove anytime.
I may have bricked the download link in the archive-card by adding the second link. So now we also have to distinguish between two possible links in the same class. The href only refers to the last entry.