DenJel

<div class="wrapper">
   <div class="inner"></div>
<div>

.wrapper {
   overflow-x: hidden;
   height: 300px;
}
.inner{
   background: blablabla;
   height: 300px;
   width: 600px; 
   position: relative;
   left: 50%; 
   margin-left: -300px;
}