I have set the Unity window resolution to 900px by 600px. Easy enough, right? The only problem is . . . the screen size isn't 900x600. I even took a screenshot and measured the pixels in MS paint. It's more like 1350 by 900.
The blue is my actual window size. You can see in the top left that it's saying my screen size is 900x600, but that's clearly false. The same thing is also occurring in the web build. It does happen to be the same ratio of width/height (3/2). So either Unity is just increasing my size by 50%, or Unity can't count, or I'm losing my mind. I've used the usual google fu abilities, but I can't find anything about this issue. Vox said he might have recalled someone else having this same problem. Assistance/explanations are greatly appreciated.
Christoph Nahr suggested changing the DPI settings, and that worked fine. I also found another quick fix for the web player. It turns out that Internet Explorer was set at a 150% zoom for some reason. I changed that back to 100%, and I'm back in business. Don't we all love IE...