纯css三角形

1.三角形

.sanjiaoxing{
        height: 0;
        width: 0;
        border: 14px solid #fff;
        border-top: 14px solid transparent;
        border-right: 14px solid transparent;
        border-left: 14px solid transparent;
}

2.边框待阴影

.sanjiaoxing{
        height: 0;
        width: 0;
        border: 14px solid #fff;
        border-top: 14px solid transparent;
        border-right: 14px solid transparent;
        border-left: 14px solid transparent;
        position: absolute;
        top: -28px;
        right: 10px;
        &:after{
            content: '';
            display: block;
            width: 0;
            height: 0;
            border-width: 15px;
            border-style: solid;
            border-color: transparent transparent #979595 transparent;
            position: absolute;
            top: -17px;
            left: -15px;
            z-index: -1;
        }