CSS lighten child elements on parent mouseover

Question

here is my problem.
I have a div which contains two other divs: basically one for header, one for content.

I'd like to lighten (change alpha level, or some other method is welcomed), when the user points the mouse over the parent div. Colors of both child divs should change and become slightly lighter. I'd like to avoid javascript if possible.

How to do this in CSS?

Answer 1

Like this?

Live Demo

Relevant CSS:

#container:hover .inner {
    opacity: 0.8
}

HTML:

<div id="container">
    <div id="left" class="inner"></div>
    <div id="right" class="inner"></div>
</div>

Irrelevant CSS:

#container {
    width: 300px;
    padding: 30px;
    overflow: hidden
}

.inner {
    width: 40%;
    height: 250px;
    background: #ccc
}
#left {
    float: left
}
#right {
    float: right
}

Truly Irrelevant CSS:

#container {
    background: #fcecfc; /* old browsers */
    background: -moz-linear-gradient(top, #fcecfc 0%, #fba6e1 50%, #fd89d7 51%, #ff7cd8 100%); /* firefox */

    background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#fcecfc), color-stop(50%,#fba6e1), color-stop(51%,#fd89d7), color-stop(100%,#ff7cd8)); /* webkit */

    filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#fcecfc', endColorstr='#ff7cd8',GradientType=0 ); /* ie */
}