My 2 cents (what I'd do):
Pick out a simple card (sticking to "Happy Birthday"), but let yourself be "drawn" to a card that looks visually attractive.
Put cash inside the card. If she doesn't appreciate how much you might give her, it's not your fault. Most likely children who find fault with a gift got too many.
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"Has not my hand made all these things, and so they came into being?" declares the LORD. "This is the one I esteem: he who is humble and contrite in spirit, and trembles at my word." – Isaiah 66:2