Making dijit.Dialog Transparent when it shows up

Question

I have a Dojo Dialog box using dijit.Dialog library. It shows up on a Rowclick event of a Dojo grid. Now when it shows up I want it to be Transparent or reduce its opacity so that Whatever was in my background i can see it and it will look good. My Dialog box is a simple <div> with data-dojo-type="dijit.Dialog".

The code is ::

<div id="terms" name ="hi" data-dojo-type="dijit.Dialog" style="height:580px;width:900px;" data-dojo-props="title:'Control Activities'" preload="true">
<center><p><strong>EDIT AN ACTIVITY </strong></p></center>
<center><table>
<tr style="height: 50px">
<td style="width: 150px" align="right"><b>ASSIGNED BY : &nbsp&nbsp&nbsp</b></td>
<td style="width: 600px" align="left"><div id="plets"><input dojoType="dijit.form.ValidationTextBox" id="dassignedbyid" name="dassignedbyname"  onfocus="hello()" required="true"></div>
<span dojoType="dijit.Tooltip" connectId="dassignedbyid">Enter Name</span></td>
<td style="width: 150px" align="right"><b>ASSIGNED TO : &nbsp&nbsp&nbsp</b></td>
<td style="width: 600px" align="left"><div id="plets1"><input dojoType="dijit.form.ValidationTextBox" id="dassignedtoid" name="dassignedtoname" onfocus="hello()" required="true"></div>
<span dojoType="dijit.Tooltip" connectId="dassignedtoid">Enter Name</span></td></tr>
</table></center>
</div>

And the Dialog box id= terms shows up on this code ::

dojo.connect(grid, "onRowClick", grid, function(){
        var items = grid.selection.getSelected();
        dojo.forEach(items, function(item){

            var v = grid.store.getValue(item, "ActID");
            getdetailsfordialog(v);
            function showDialog(){
                dojo.require('dijit.Tooltip');
                dijit.byId("terms").show();
                document.getElementById('closelabelspan').style.display = 'none';
                document.getElementById('holdlabelspan').style.display = 'none';
                document.getElementById('startlabelspan').style.display = 'none';
                document.getElementById('cancellabelspan').style.display = 'none';
                document.getElementById('updatelabelspan').style.display = 'none';
            }

            showDialog();
            }, grid);
      });

Now i want that when this dialog box(terms) pops up it is transparent. I have tried one CSS also but that ain't working for me ::

<style>
div.transbox
  {
  width:900px;
  height:580px;
  background-color:#FFFFFF;
  border:2px solid black;
  opacity:0.6;
  filter:alpha(opacity=60); /* For IE8 and earlier */

  }
</style> 

I am using IE8.

How to do this ? Thanks ..

Function showDialog() edited ::

function showDialog(){
                dojo.require('dijit.Tooltip');
                dijit.byId("terms").on("show", function() { dojo.style(this.domNode, "opacity", 0.3); });
                dijit.byId("terms").show();
                document.getElementById('closelabelspan').style.display = 'none';
                document.getElementById('holdlabelspan').style.display = 'none';
                document.getElementById('startlabelspan').style.display = 'none';
                document.getElementById('cancellabelspan').style.display = 'none';
                document.getElementById('updatelabelspan').style.display = 'none';
            }

Answer 1

Programatically

    var dia = new dijit.Dialog({
        title: "Click me!",
        onShow: function() {
            var me = this;
            // show routine sets opacity to 1, wait till it has and reset
            // second style call sets the underlay as well
            setTimeout(function() {
                dojo.style(me.domNode, "opacity", 0.4);
                dojo.style(dojo.byId(me.underlayAttrs.dialogId + me.underlayAttrs["class"]), "opacity", 0.4);
            }, 1000);
        },
        content: 'simple contents'
    });
    dia.startup();
    dia.show();

Via markup;

<div data-dojo-type="dijit.Dialog" style="height:580px;width:900px;" 
   data-dojo-props="title:'Control Activities'" preload="true">

   <script type="dojo/method" data-dojo-event="onShow" data-dojo-args="">
            var me = this;
            // show routine sets opacity to 1, wait till it has and reset
            // second style call sets the underlay as well
            setTimeout(function() {
                dojo.style(me.domNode, "opacity", 0.4);
                dojo.style(dojo.byId(me.underlayAttrs.dialogId + me.underlayAttrs["class"]), "opacity", 0.4);
            }, 1000);
   </script>
</div>