The hex color #2e3f3f is a dark color. The web-safe version is Hex
#333333. A complementary color is
#D1C0C0. The grayscale version is
#393939. A 20% lighter version of the original color is
#617272, and Hex
#000C0C is the 20% darker color. If the color is saturated by 10%, you get
#2D4040. If the color is desaturated by 10%, the color
#2F3E3E is obtained.