Input fields cannot be clicked on form with absolute positioning on iOS7

I have a form with position: absolute, on the bottom of a viewport. When I click any field, it triggers touchstart event, keyboard pops up, but field doesn't get click event so it's not focused. It only happens when form is below the keyboard. If I change bottom: 0 to top: 0 and form appears on top of a viewport, everything is fine. This bug doesn't occur on iOS6.