Cat-proof Dog Doors and/or fences?

My wife and I just bought our first house, and we hope to get a dog this spring. Due to our unpredictable and often late-night schedules, we will need to install a dog door for the back door.

We have two indoor kittens (11 months old). Is there any kind of "cat-proof" dog door that will allow a dog in and out without letting a cat out? Maybe a certain weight that cats can't push but a strong dog can?

And then as a fail-safe, I might want to install some cat-proof fencing around our back yard -- any suggestions on a cat-proof fence that won't make my yard look like a prison?

Thanks,
chris.

The electronic/magnet operated doors will only allow an animal wearing an electronic 'key' to open them. The problem usually is that a cat quickly learns that if it can't open the flap and another animal can, whether cat or dog, it can get through at the same time by sticking close. I have had that problem when trying to keep kittens or sick cats inside.