You have used white background and red (or black) font. Would it be possible to increase the size of the font, by 1 or 0.5? Alternatively, a different font that has different typeset (uppercase/"capitals"). Similarly with the spades/clubs symbols.
They read fine on a screen but on postcard sized paper, particularly with artificial light (late in the evening), I had some problems 'reading quickly'. Red helped, yet black font was the main troublemaker :)