#caja {
    display: block;
    width: 100px;
    height: 100px;
    background: rgba(255,0,0,0.4);
    font-size: 12px;
    position: absolute;
    top: 0;
    left: 0;
    
    transform: ;
-webkit-transform: perspective(500px) rotateX(180deg);
-moz-transform: perspective(500px) rotateX(180deg);
-o-transform: perspective(500px) rotateX(180deg);
-ms-transform: perspective(500px) rotateX(180deg);
transform: perspective(500px) rotateX(180deg);


    
    /* transiciones */
    transition: all 0.4s ease;
}
    
#caja:hover {
    background: rgba(0,0,255,0.4);
    transform: rotateX(0deg);
}