<div class="contain"> <div class="left"></div> <div class="left"></div> </div> <hr> <div class="contain BFC"> <div class="left"></div> <div class="left"></div> </div>
.contain { background-color: #eee; border: 4px solid red; } .left { float: left; background-color: #444; width: 100px; height: 100px; } .BFC { overflow: hidden; }