Light hanging help

[medi]

I am building a new hanging lighting fixture for my tank. I am going to suspend the fixture with 1/8" steel cable. As you can see in my horrible sketch I am going to have two cables attached to the ceiling, and then each cable is going to split and connect at four points on the frame of the fixture. I need the fixture to be able to adjust vertically so I can raise the lights off of the tank, and I also want the cables to be easily adjusted at the four connection points on the frame so that I can easily level the fixture. Also, this is in my living room so it needs to look aesthetically pleasing or else my wife might kill me. I've got a few different ideas of how I'd like to accomplish this, but I wanted to throw this out there and see what everyone else's thoughts are. I am open to all ideas so throw it out there. Thanks