KDE 2 defaulted to a vertical gradient of deep blue fading into silver. To be honest, it looked a bit washed out when compared to the default gradients of KDE 1. However, if the display only supported 8-bit color or less, the top color of the gradient was used as a flat background instead - which in my personal opinion looked a lot better. In addition to these two colors, you could pick from 40 default swatches (included below), the Netscape Navigator "Web"-palette, and a Gimp "Royal"-palette (both not included).