Thanks for the screenshots!

I have checked them and you have missed curly braces there as I can see from your screenshot.

May I know which device resolution you are using? You have put starting point as 1500px. If you are seeing the site with a lower resolution device that 1500px then it will not reflect either.

However, you can use the followoing code instead:

@media (min-width: 1200px){
.sppb-row-container {
    max-width: 1400px;
}
}

Let me know if it solves the issue or not.

Best Regards