low opacity whit out toching child nods
#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>