HI Chris, I've made a min/max validator. It can show error message when input value is not in the given range.
I made this validator for the <input> whose clazz is "number", "number-required", "non-negative-number-required", "positive-number", "positive-number-required". You have to add these clazz to enable the min/max validator. e.g. <f:number clazz="positive-number" min="5" max="70">
But if the number is out of range, it won't limit the stepper buttons.
Just check the demo and check if the content of the error message is good or bad.
If it's ok, I'll make a pull request.