Improve fonts

People are having problems reading everything.

We should consider changing to weight of 400 instead of 300.

Blog entries should move to a serif font.

And buttons should always be bold.

Thanks for writing down @Marc.Radulescu his remark!

mentioned in merge request !143 (merged)

Status changed to closed by commit 43e9af

Thanks @JobV . I forgot to do this myself.

mentioned in commit 3a599d41