.message-box {
    position:relative;
}
.triangle-border {
    position:absolute;
    top:30px;
    overflow:hidden;
    width:0;
    height:0;
    border-width:10px;
    border-style:dashed dashed dashed solid;
}
.tb-border {
    right:-10px;
    border-color:transparent transparent transparent red;
}
.tb-background {
    right:-18px;
    border-color: transparent transparent transparent #fff;
}