SOURCE

<div class="main">
  <div class="content">content</div>
</div>
<div class="sub">sub</div>
<div class="extra">extra</div>

.sub {
  width: 100px;
  margin-left: -100%;
  background: red;
}
.extra {
  width: 200px;
  margin-left: -200px;
  background: blue;
}
.sub, .extra {
  float: left;
}

.main {
  float: left;
  width: 100%;
}
.content {
  margin: 0 200px 0 100px;
}