You may color the base lines but they need to be still visibly darker than the design itself.

You made add a soft light halo affect around the croc's base.

These can a few point lighter or dark than the base color unless a marking is touching the tuft. 

ex. Hood covers the neck tuft and will sit above the free allowance.

Color must come from the base color and cannot be different color.

Rainbow does not affect tufts.

Claws can be lighter or darker and may have a faint shine on them. The color can be derived from the base or match a marking color that touches the feet. 

They should not be a neon color without one of the following genes: Tropical, Iridescent or Luminescent. 

Pink skin can only peek out from under white fur.

So as long as a marking is white and in an area where fur would be thinner pink skin can show.