When the option to hide the datepicker's controls is false, the calculations in the open() function to determine where the calendar should be shown are being done before the 'jcalendar-hide-controls' class is added to the container. This causes the calendar to appear with a large cap between the calendar and the control it is associated with when the calendar is shown above the control. IT also affects the calculations to determine whether the control should appear above or below the control so it will be visible on the screen.

The code to add that class must be moved to be before calling open() to show the calendar:

        // Controls
        if (obj.options.controls == false) {
            calendarContainer.classList.add('jcalendar-hide-controls');
        }

        // Default opened
        if (obj.options.opened == true) {
            obj.open();
        }