I have a list to track customer training. Two of the trainig items are recurring; Ethics - annual and GPC Refresher - biannual (every two years). The due dates for each training requirement were created using a calculated column. I would like each cell of those calculated column dates to highlight yellow when they are 30 days out, and highlight red when they are due and past due. I am running SP2013, on-prem, and do not have Designer. I've been able to use a script editor web part to change the font color of certain words in another list that worked great, but highlighting the cell of calculated column dates is over my head. Any help is much appreciated!
Calculated columns are updated only when the item itself is updated, so for your indication to be always up-to-date, you'll have to use client-side tricks.
You can adapt ViewMaster. Start from a new calculated field with this formula:
="<img src=""_layouts/images/blank.gif"" onload=""console.log('ViewMaster executed on: " & [Title] & " ');"">"
If you're lucky then Danny Engelman himself will help you :)