How can I put "first name / last name" field on same line?

I'm trying to put the "first name / last name" field on the same line. For some reason it's not letting me. Any suggestions?

Thank you.

I have checked the form you provided and seems like you were able to display the fields as you need, here is how it currently displays on a desktop computer: 

Reducing the screen size: 

However, if you need more help, please let us know and we will be glad to assist you. 

Hi Kevin! Yes, I managed to fix the form to have the first name / last name field on the same line :) This thread can be closed.

Thanks.