Is this your website that you had applied the custom css?
I am not seeing it in the source code.
Please apply via Appearance -> Theme Options -> Custom CSS
Don’t use the customizer.
Do you have a server cache or cache plugin such as W3 Total Cache or WP Super Cache?
If yes, you will need to clear it’s cache content.
Let’s try to get the codes to show up first, before proceeding any further.