Thank you both for your response.
Excavator: I've saved the validation links in your sig. That's going to start being my go to before posting any questions.
I replaced the height specification with min-height which seems to be behaving the correct way while still spacing things nicely.
Did some reading on the id vs class from a few sources. From what I understand, they behave the same but classes should be used for repeating elements and an id for a singular element. I cannot fully understand why, however I will keep reading.
Learning how to float appropriately is something I will have to mess around with a lot more. I tried putting my .box inline but I could not accomplish the same effect without floating the .box.
I've got some more reading and experimenting to do. Thank you for steering me in the right direction.