I have dates in column D in Google Sheets.  I want the cells to highlight to red if 30 days have passed and there is not a comment date in column f.

*Example:* 
Column D:  Submittal Date  6/29/2019
Column F:  Comments Received (date) 
If I don't receive comments within 30 days of submittal date the a cell should turn red to alert me to follow up.