How to apply an opacity without affecting a child element with html/css?

Question

I want to achieve this using html and css:

I have tried to set the opacity of the container to 0.3 and the box to 1, but it doesn't work: both divs have 0.3 opacity.

jsFiddle of my try here

The effect I am trying to achive is a popup box that comes on top of the page. It is highlighted by fading the content below (by lowering the opacity).

Answer 1

As far as I know you can't do it in a simple way. There a couple of options here:

1. Use absolute positioning to position box "inside" the container.

   #container {
       opacity: 0.3;
       background-color: #777788;
       position: absolute;
       top: 100px;
       left: 100px;
       height: 150px;
       width: 300px;
   }
   #box {
       opacity: 1;
       background-color: #ffffff;
       position: absolute;
       top: 110px;
       left: 110px;
       height: 130px;
       width: 270px;
   }

   <div id="container"></div>
   <div id="box">
       <p>Something in here</p>
   </div>

2. Use Javascript - almost the same as above, but position and size don't have to be hardcoded.