html,
body {
  width: 100%;
  height: 100%;
  margin: 0;
  padding: 0;
  font-family: sans-serif;
}
.header {
  margin: 10px;
}
.container {
  width: 660px;
  margin: 0 auto 0;
  height: 100%;
}
.pane {
  float: left;
  width: 300px;
  margin: 10px;
}