Be responsive for God’s sake
How many times do I have to write this down?!
Simple things like this can ruin your whole strategy. Always go for responsive themes.
Imagine someone who want to do shopping on his phone and no matter how much he wants he will never actually do it, because your theme will be messed up.
Not to mention that because we are all lazy f*cks, we would never go on that site for shopping even on a desktop.