full screen css 3d cube that rotates to specific sides on click - repost

hi, I have a very small development project that I'm having a hard time with. I'd like to make a 3d css3 cube that rotates to specific sides by clicking on specific buttons, not super complicated, but I'm having a hard time finalizing it. Here is what I've gotten going so far, but as you can see the sides of the cubes are to close to the center [login to view URL] I know this has something to do with the translateZ but I can't quite get it to work. I need someone to make this adjustment for me, it needs to be able to be fullscreen on matter the screen, which shouldn't be so bad. I'll need you to explain this to me after you finish it. Please don't apply for this if you're not familiar with css3 3d attributes. If you are familiar with them this should be a pretty easy job.