Hide a div, show another div when student owns class

I'm SO close to my Marketpress / Coursepress customization that will allow our customers buy as many products and courses as they want in one transaction, I just have ONE outstanding issue I need to work out, and I'm hoping you can give me a little input as well.

My workaround: instead of using the coursepress buy page and enroll box buttons (which only allow customer to buy one class at a time and nothing else), I'm making use of the Marketpress category page you guys helped me set up here:

http://dearhandmade.staging.wpengine.com/shop/online-workshops/

And then, on each of the individual class pages (which are coursepress info pages), I used css to hide the Coursepress enroll-box class. And I inserted the Marketpress buy button shortcode into the long description of the class, so if someone goes to buy it, everything else in their cart isn't deleted:

http://dearhandmade.staging.wpengine.com/online-workshops/craft-show-success-online-workshop/

My very last issue: I need to bring back the enroll-box class when someone who owns the class is logged in, so when they go to their class dashboard, and click to go to their class, they can see the "Start Learning" button. I also need to hide the div that includes the marketpress buy button shortcodes.

Both of those are easy fixes with display:none and display:block css rules... but I'm having trouble getting a handle on writing the css for someone who is both logged in AND owner of the class.

For example - student owns Craft Show Success online workshop, and logs in to site to start learning. I want to hide the buy button on that class description page because they already own it. If I add this css rule:

.logged-in .mp_button_addcart {
display: none;
}

Then anyone who is logged in will not see the buy button, regardless of whether or not they own the class. And if someone's logged in, and they own that class but not others, the buy button will be hidden on all the other workshop description pages.

So here's the conundrum: What do I add to that css rule above so it ONLY hides the .mp_button_addcart class on classes where user is BOTH logged in AND owner of the class on that page? If you can help me out with that one, I'm sure I can figure out the others.

Thanks in advance for a quick answer, we need this site to go live soon.