The hex color #687fc1 is a dark color. The web-safe version is Hex
#6666CC. A complementary color is
#97803E. The grayscale version is
#8D8D8D. A 20% lighter version of the original color is
#9BB2F4, and Hex
#354C8E is the 20% darker color. If the color is saturated by 10%, you get
#647EC6. If the color is desaturated by 10%, the color
#6C80BC is obtained.