What color is Book, Designing Interactions ?

Source Crayola® CSS3 CSS4
#aaa4ae
 
#979aaa
manatee
#a9a9a9
dark gray
#a9a9a9
darkgrey
#7e7886
 
#757575
sonic silver
#808080
grey
#808080
grey
#534f5a
 
#414a4c
outer space
#696969
dim grey
#696969
dimgrey