Contrast isn't the only indicator of readability. The font choice here is IMHO terrible for screen. It's much too thin. Taking this to the logical extreme - ju

Contrast isn't the only indicator of readability. The font choice here is IMHO terrible for screen. It's much too thin. Taking this to the logical extreme - just for fun - imagine a the perfect contrast score of Vantablack™ on Spectralon white. It wouldn't matter if the typeface stroke widths were only a micron wide. It would still be unreadable.