Grey on white is atrocious - their graphic design person should know better. The best pairs of colors, to capture maximum optical acuity and psychological attention are...

91% Black on White, White on Black

89% Black on Yellow, Yellow on Black, Black on Beige, Beige on Black

84% White on Red, Red on White, White on Brown, Brown on White

There are lots of pother combos between 84% and the low 70s. When you get close to 70%, acuity and attention are greatly diminished and should not be used.

Grey/White combinations are 78%