I’m trying to use the System.Drawing.Color namespace. I’m not able to define it at the top of the class:

However, I can reference it within the class. That is, I can use this line of code, and it works:
txtBox.BackColor = System.Drawing.Color.LightPink;
… but I’d rather just be able to do this:
txtBox.BackColor = Color.LightPink;
If it’s a matter of a missing reference/dll, why am I able to make reference to System.Drawing.Color in my code?
That’s because it isn’t a namespace.
System.Drawingis the namespace, andColoris a structure (struct).EDIT: Additionally, I’d advise to use a product such as ReSharper, which can correct stuff like this almost automagically. ReSharper rules!