Why is turbox tax saying my refund is negative in Grey font color

That means instead of getting a refund you owe tax.  You can look at line 37 of your Form 1040 to see the amount you owe to the IRS.

PREVIEW 1040

https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filing

Click on Tax Tools on the left side of the screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.

The negative sign and grey color indicates that given what you have entered so far in TurboTax, you owe taxes this year. Once you are done with all the interviews and entering data and if you get the same indication, you will have a payment due to the IRS by 18 Apr.