A dark blue minimalist birthday card features Euler's identity e^i t + 1 = 0 in glowing gold, with "HAPPY BIRTHDAY" below.

A clean, minimalistic birthday card with the equation \(e^{i\pi }+1=0\) as the centerpiece. The design should feel elegant and profound. The background should be a gradient of deep blue to black with subtle, geometric patterns overlaying it, like faint golden lines representing a network of connections. The equation should glow softly in a vibrant, ethereal white or gold font, as if emitting its own light. See more