Problem with reversing columns on mobile

I have purchased the Veterinary Care theme and I want to reverse a 2 column row I have created, but when I use custom CSS - "display : flex; flex-direction : column-reverse ;  it does not reverse the column. How can I name the row correctly so I can use it in CSS?

Hey please check it out,

You can click on Main row Edit button or nested row's edit button

Then you can add ID or extra class. 

To use id you can use it like #myid and to use class you can use as .myclass

Here you can add them.