Changes
float: left;
margin: 0 0 10px 10px;
}
.externalimageHolder .caption {
position: absolute;
width: 100%;
height: 50px;
bottom: 0px;
left: 0px;
color: #ffffff;
background: green;
text-align:center;
font-weight:bold;
opacity:0.7;
}
