.boxgrid {
   width: 300px;
   height: 200px;
   margin:10px;
   float:left;
   background:#646452;
   border: solid 2px #8399AF;
   overflow: hidden;
   position: relative;
   color: #000;
}
.boxgrid img {
   position: absolute;
   top: 0;
   left: 0;
   border: 0;
}
.boxcaption {
   float: left;
   position: absolute;
   background: #bbb;
   height: 160px;
   width: 100%;
   opacity: .8;
   /* Pour IE 5-7 */
   filter: progid:DXImageTransform.Microsoft.Alpha(Opacity=80);
   /* Pour IE 8 */
   -MS-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=80)";
}
.captionfull .boxcaption {
   top: 200px;
   left: 0;
}
.caption .boxcaption {
   top: 160px;
   left: 0;
}