.caret-up {
    width: 0; 
    height: 0; 
    border-left: 4px solid rgba(0, 0, 0, 0);
    border-right: 4px solid rgba(0, 0, 0, 0);
    border-bottom: 4px solid;
    
    display: inline-block;
    margin-left: 2px;
    vertical-align: middle;
}
.vision
{
background:url(../images/vision.png);
width:100px;
height:100px;
}
.vision:hover
{
background:url(../images/vision_h.png);
}