The trick, I realised, was to try and capture the essence of PayPal's brand. The client could not find their brand guide, so I had to figure out PayPal's brand essence.
Though a visual research of PayPal's brand images and existing PayPal websites, I realised their brand essence could be expressed as 'transparency'.
In application, this meant thinking of how we could render the surface to be glass-like. I played with transparent overlaps, subtle gradients, and a lot of blue to achieve the distinct PayPal feel of a cool, clear, glass-like visual experience.