Dark theme - unable to see dates in new date selector control

[DeanMarkTaylor (Dean Taylor)]

/admin/reports/visits and other report pages

/admin/email/preview-digest

And when selecting a year:

[codinghorror (Jeff Atwood)]

One for @zogstrip then.

[zogstrip (Régis Hanol)]

Just fixed it

https://github.com/discourse/discourse/commit/ded03a1aa4ebf72d73187e7214f72fc57a9a8dac