The hex color #687fc0 is a dark color. The web-safe version is Hex
#6666CC. A complementary color is
#97803F. The grayscale version is
#8D8D8D. A 20% lighter version of the original color is
#9BB2F3, and Hex
#354C8D is the 20% darker color. If the color is saturated by 10%, you get
#647EC5. If the color is desaturated by 10%, the color
#6C80BB is obtained.