.claseadd {
                color: #ff0000
            }
            .caja {
                width: 150px;
                height: 150px;
                position: relative;
                float: left;
                border: 1px solid #000
            }
            .clase_fv {
                background-color: green
            }
            .clase_rj {
                background-color: red
            }