Absolute Position PopUp Div Doesn't Show in FullCalendar
===

I want to display a popup when an event is clicked in FullCalendar.  Based on my CSS, the div is created and positioned properly, however, the div is not visible.  Visibility is not set to 'hidden'.  Note, when I change the position to 'fixed', it does show.  I've tried messing with the z-index to no avail.

CSS: 

    ._detail {
	  position:absolute;
	  left:-260px;
	  font-size:1em;
	  padding:5px;
	  height:150px;
	  width:250px;
        background-color:lightgrey;
	    border-radius:4px;
	    border:1px solid darkgrey;
    }

Basic JS: 

    eventClick: function(calEvent, jsEvent, view) {
      // create div with class '_detail', fill it with stuff
      jsEvent.target.appendChild(_div); }