JSFiddle - React, Tailwind, and code Playground

HTML

<div class="outer">
    <div class="inner">
        Inner div
    </div>
    Outer div. 
Notice the transparency of Outer div.
</div>

CSS

body{
    background-color: #759;
}
div {padding:5px;}
.outer{
    background-color: rgba(255,255,255,0.9);
    filter: progid:DXImageTransform.Microsoft.Gradient(GradientType=1,startColorStr="#E6FFFFFF",endColorStr="#E6FFFFFF");
    -ms-filter: progid:DXImageTransform.Microsoft.Gradient(GradientType=1,startColorStr="#E6FFFFFF",endColorStr="#E6FFFFFF");
}
.inner {
    background-color: #FFF;
}