Slider number overlays Tutor feedback

[kirsty-hames]

Subject of the issue

When using Tutor "_type": "overlay" in a course, .slider__number-selection (user selection) and .slider__number-model-answer (correct answer) display over the Tutor feedback.

Steps to reproduce

Enable Tutor "_type": "overlay" in a course, as per example.json.

Go to course Slider and submit. Toggle "Show correct answer" / "show your answer" buttons to see both instances when feedback is displayed.

Expected behaviour

Slider numbers should be hidden behind the Tutor overlay.

[kirsty-hames]

I can't see that the z-indexstyles are needed but looks like these were added during the v5 release so this will need testing before removing.