Date field calendar popup z-index issue

[mudrasamey]

Describe the bug
When using calendar widget with option button, if the calendar opens over the option button, the selected option button shows over the calendar.

To Reproduce
Steps to reproduce the behaviour:

1. Add a date field and option button to a form in such a way that they are placed one below the other and the calendar popup opens over the option button.
2. Select any option & open the calendar widget. The option button will be seen through the calendar popup

Expected behaviour
When a calendar popup opens over any other form element it should be clearly visible and no form element should overlap it.

Actual behaviour
Currently the selected option button overlaps the calendar popup

Screenshots