Col. B.,
Depends!
Officers on the General Staff were to wear dark blue trousers. Officers of Infantry and Artillery wore sky blue pants. Officers of Dragoons of the grade of Col., Lt. Col. and Major were authorize dark blue pants while company grade officers wore the light blue.
Joel Jacobson publishes the 1847 Regs. My buddy that I am visiting checked his original copy.
Hope that this answers your particular question.