.triangle{
    width: 0px!important;
    height: 0px!important;
    border-left: 100px solid transparent;
    border-right: 100px solid transparent;
    border-bottom: 150px solid red;
    position: relative;
}
.triangle::before{
    position: absolute!important;
    content:'';
    width: 0px;
    height: 0px;
    top:75px;
    left: -87px;
    right: 0px;
    bottom:0;
    margin: auto;
    border-left: 87px solid transparent;
    border-right: 87px solid transparent;
    border-bottom:138px solid #fff;
}