.zone { width: 720px; margin-left: auto; margin-right: auto; }

.grid-12-1, .grid-12-2, .grid-12-3, .grid-12-4, .grid-12-5,
.grid-12-6, .grid-12-7, .grid-12-8, .grid-12-9, .grid-12-10, 
.grid-12-11, .grid-12-12 {
  margin-left: 5px; margin-right: 5px; float: left; position: relative; float: left; display: inline;
}

.grid-12-1 { width: 50px; }     
.grid-12-2 { width: 110px; }
.grid-12-3 { width: 170px; }
.grid-12-4 { width: 230px; }
.grid-12-5 { width: 290px; }
.grid-12-6 { width: 350px; }
.grid-12-7 { width: 410px; }
.grid-12-8 { width: 470px; }
.grid-12-9 { width: 530px; }
.grid-12-10 { width: 590px; }
.grid-12-11 { width: 650px; }
.grid-12-12 { width: 710px; }