child1

width: 580px;
margin-bottom: 30px;
border: 5px solid #0d4100;

child2

float: left;
width: 285px;
margin-bottom: 0;
border: 5px solid #236701;

dummy text

child3

float: right;
width: 285px;
margin-bottom: 0;
border: 5px solid #5ea20d;