No Tom, only if they are not equal.
Image issue above happened when I set custom css value to 20px but the seperating space in elements was 15px. Then I got the offset problem. Only happened with that container (the slider). All other areas were fine.
So long as the values are equal in both custom css and sperating space …. it’s fine.
My Website is set equal in both now and is running ok on both pc and mobile device.
Excuse the messy site, still work in progress. 🙂