Fixed width div on left, fill remaining width div on right
Try removing the float:left and width:100% from .header-right — the right div then behaves as requested. .header { float: left; background: #efefef; background-repeat: no-repeat; width: 240px; height: 100px; } .header-right { overflow: hidden; background-color: #000; height: 100px; } <div class=”header”></div> <div class=”header-right”></div>