Mobile Version - New Responsive Engine

I’m trying to replicate a simple index mobile version for my website. I want individuals to have the ability to “Sign Up,” “Login,” and “Contact Us” for now. I have the layout setup (including workflows), however, I’m struggling to align the mobile version the correct way on my phone. Do I make the mobile page responsive? Do I make a quick page (set the widths to 300px) and build on there to make it fit? Any tips or videos are greatly apprecaited. I will be watching “A Guide to the Responsive Engine” on YouTube tomorrow.