Latest Confluence releases (starting from 6.7.0) include new, refreshed layout and refreshed fonts.
However "Created by..., last modified by... on ..." characters are difficult to read.
It is possible to adjust font-weight from 300 to 400 in global custom stylesheet :

page-metadata {
font-weight: 400;
}

.page-metadata ul li a:link {
font-weight: 400;
}

and then fonts look much better.

Feature suggestion

Increase default font weight from 300 to 400