Shortcode Alignment (Center)

Help! I’ve spent the last 3 hours going crazy!!

I’m not a CSS expert or coder so this is a struggle for me.

But Im trying to simply have control over the shortcode and automatic buttons that Easy Digital Download inserts. For some reason, they are stuck on a left margin alignment. I tried EVERYTHING I can think of from html centering, div tag centering, and even playing around in the EDD.css file, but I still haven’t figured it out. How hard is it to just center an “Add To Cart” button on my downloads item page?? Please help! I will be eternally grateful.

The page I need help with: [log in to see the link]