Correcting width for mobile browsers

Steps to reproduce

1. With a mobile browser or a desktop browser whose size has been reduced in width.
2. Visit the page at /library/artists/XXXXX

What happens?

Somes UI is broken, like screenshot at the end of this message.

What is expected?

Context

The CSS calculates dynamically the width according to that of the screen, which poses problem on mobile :
width: calc(33.33333% - 2em);

Funkwhale version(s) affected: 0.18.1

We can fix it with a correct min-width in CSS. ^^