Small UI improvements : size with units (and kilo) for download

Problem
The very first time I logged in, I noticed a string of numbers that I didn't understand right away (there were so many numbers that I didn't make the connection between the “/” and “Downloading” until later).

Improvement
It would be clearer if a unit were added.
And to make that unit visible, use multiplication factors or prefixes. Seeing “339 Mb/639 Mb” seems clearer to me, doesn’t it?

Yes, it’s a small detail, but as I was getting started, it’s one of those little things that can be confusing.