body{ text-align: center; margin: 0; padding: 0; background-image: url(../img/fondo.jpg); background-repeat: no-repeat; }

.container { float: center; position: absolute; top: 50%; left: 50%; width: 1000px; height: 600px; margin: -260px 0 0 -500px; 
             overflow: visible; visibility: visible; display: block }
.center { float: center; width: 1000px; height: auto; margin: 0; padding: 0; }
.bottom { float: center; width: 1000px; height: auto; margin: 0; padding: 0; }
.dx { float: left; width: 500px; height: auto; margin: 0; padding: 0; }
.sx { float: left; width: 500px; height: auto; margin: 0; padding: 0; }