We can select different styles for mobile, desktop.
Style for Desktop:
Style for Mobile:
Not selecting different styles as expected
If Styles for desktop, mobile not selected as expected, it might be due to a cache issue. Some of the cache(cache plugin, servers side cache) creates only one static file per page and the same page loading for desktop, mobile.
There are two ways we can fix this issue:
Method 1: If there is an option to enable to detect devices(seperate cache for mobile) on cache plugins installed on your website, enable it.
Method 2: Check this, If styles for mobile, desktop not selected as expected(due to cache)