Talk to an intellectual property attorney about this. There are plenty of stories out there about professional sports leagues coming down hard on people that dance close to that line.
In no way am I offering you legal advice, and in no way has my comment created an attorney-client relationship. You are not to rely upon my note above in any way, but insted need to sit down with counsel and share all relevant facts before receiving fully-informed legal advice. If you want to be completely sure of your rights, you must sit down with an experienced criminal defense attorney to be fully aware of your rights.
For colors alone? That seems unlikely. That is, we're talking about a mix of green and yellow. If that were an infringement with respect to the Packers, it would also be an infringement with respect to the Oakland A's... If there are identifying marks, that's different. An Attorney would need to review to provide a more precise answer.
Unlike most of the other questions about using the NFL related trademarks, you are merely seeking to use the same colors that NFL teams use. So long as you do not mention the Green Bay Packers, the NFL, or any of their teams, then you should be okay. Definitely run it by an intellectual property attorney prior to posting them on your website.
The answer to this question is for informational purposes only and does not form an attorney-client relationship.