affect top div opacity without affecting childrne

#container {<br /> border: solid gold 1px;<br /> width: 400px;<br /> height: 200px;<br /> background:rgba(56,255,255,0.1);<br /> }</p> <p>#box {<br /> border: solid silver 1px;<br /> margin: 10px;<br /> width: 300px;<br /> height: 100px;<br /> background:rgba(205,206,255,0.1);<br /> transition: 2s background;<br /> }</p> <p>// if you then want to apply an animation, do it on background-color instead of opacity