<!-- webkit-test-runner [ internal:LayoutFormattingContextEnabled=true internal:LayoutFormattingContextIntegrationEnabled=false ] -->
<style>
.container { 
    position: absolute;
    padding-top: 300px;
    border-top: 100px solid red;
}
.float {
    float: left;
    width: 200px;
    height: 200px;
    background: green;
}
</style>
<div class=container>
    <div class=float></div>
</div>