Taken from the IBJJF Uniform section. 

https://ibjjf.com/uniform

Picture of No-Gi uniform can be downloaded here

Information in short:

SHIRTS AND RASH GUARDS

You must wear a rashguard or other elastic shirt that is skin tight. The color has to be black, white or black / white.

At least 10 % of the rashguard has to be the color of your belt. 100% of your belt color is also permitted.

For example a blue belt will need a rashguard with 10% up to 100% of the color blue on the rashguard.

SHORTS FOR MEN

Board shorts in the color black, white, black/white or the color of your belt. No pockets allowed.

You are permitted to wear tights under your shorts. Tights must be in the color black, white, black/white or the color of your belt.

Men are not allowed to only wear tights, you must have shorts too.

SHORTS FOR WOMEN

Same rules as for the men. The main difference is that women is allowed to wear tights only, if they wish too.