.ajax__calendar_container { z-index : 1000 ; }
<style type="text/css">
.ajax__calendar_container { z-index : 1000 ; }
</style>
.ajax__calendar {
position: relative;
left: 0px !important;
top: 0px !important;
visibility: visible; display: block;
}
.ajax__calendar iframe
{
left: 0px !important;
top: 0px !important;
}
<fieldset> some content... including ajax popup </fieldset>
<fieldset> some more content </fieldset>
<fieldset style="z-index: 2;"> some content... including ajax popup </fieldset>
<fieldset style="z-index: 1;"> some more content </fieldset>