#caption {
    position: fixed;
    bottom: 40px;
    left: 50px;
    font-family:"Comic Sans MS";
    font-size: 50px;
    text-decoration: bold;
    color: black;
    line-height: 30px;
    height:30px;
    width: 100%;
    white-space: nowrap;
    -moz-animation:  caption 50s linear 0s infinite;
    -webkit-animation:  caption 50s linear 0s infinite;
}
@-moz-keyframes caption { 
    0% { margin-left:120%; } 100% { margin-left:-4200px; }  
}
@-webkit-keyframes caption { 
    0% { margin-left:120%; } 100% { margin-left:-4200px; }  
}