styling for Native app 9.3.0

My Scenario: I would like to build a native app and I could see the bank account details as below: Created 2 containers inside a container as shown below and created custom JS class . Can anyone please help me how to create a Custom JS file for this requirement or is there any other way to give styling ?    
1 answers

Have you checked the native styling docs yet: and, since you are using 9.3.0