The hex color #213d3c is a dark color. The web-safe version is Hex
#333333. A complementary color is
#DEC2C3. The grayscale version is
#333333. A 20% lighter version of the original color is
#54706F, and Hex
#000A09 is the 20% darker color. If the color is saturated by 10%, you get
#1F3E3D. If the color is desaturated by 10%, the color
#233C3B is obtained.