#container {width: 1440px;
            position:absolute;
             margin:0;
            /*top: 50%;*/
            left: 50%;
            /*margin-top: -400px;*/
            margin-left: -512px;
            }


.caption {
    font-family: Verdana, sans-serif;
    font-size: 20px;
    float: left;
    width:100%;
    margin: 0;
    padding: 0;
    position: relative;
    overflow: hidden;
}

.caption span {
    /* ... */
    display: block;
    }
.caption:hover span { display: block; }


.caption img {
    float: left;
    margin: 0;
    padding: 0;
    background: #fff;
    border: none;
}



.caption span {
    float: left;
    margin: 0;
    padding: 10px;
    width: 100%;
    color: #dedede;
    
    background: #222; /* browser che non supportano rgba */
    background: rgba(0,0,0,0.7);
    position: absolute;
    left: 0;
    top: 0;
}

.caption span strong {
    font-weight: bold;
    font-size: 25px;
    text-transform: uppercase;
    display: block;
    padding-bottom: 5px;
}