sizeof() struct w/ nested enum returns wrong size

I have the following situation compiling using Visual Studio 2003:

#include "stdafx.h"
#include <iostream>
#include <limits>

namespace Outer{
      class Xyz {
      public:

            typedef struct {
                  enum { classConstant1 = 0x0001,
                              classConstant2 = 0x0002,
                              ForceSize2Bytes = 0x7FFF
                  }; // end enum
            } Constants; // end struct

      }; // end class Xyz

} // end namespace Outer

int _tmain(int argc, _TCHAR* argv[])
{
      std::cout << "The sizeof() Outer::Xyz::Constants = "
                    << sizeof(Outer::Xyz::Constants)
                    << std::endl;
      std::cout << "Outer::Xyz::Constants::ForceSize2Bytes = 0x"
                    << std::hex
                    << Outer::Xyz::Constants::ForceSize2Bytes
                    << std::endl;

      std::cin.ignore((std::numeric_limits<std::streamsize>::max()),
'\n');

      return 0;
} // end main()

Here's the output:

The sizeof() Outer::Xyz::Constants = 1
Outer::Xyz::Constants::ForceSize2Bytes = 0x7fff

The struct size is reported as one while the cosntants clearly output
a 2 byte value.

Does anyone knwo what's going one?

Thanks, HJS