Very old article but even today it gives us solutions!

I added it "radius"and got a tremendous result.

Thank you.

#parent {border-radius: 15px;
border: 2px solid #cccccc;
padding: 10px;
width: 80%;
height: 450px;}

#floater {
float: left;
height: 50%;
width: 100%;
margin-bottom: -50px;
}
#child {
clear: both;
height: 100px;
}