CSS画三角形的快捷方式

效果图

代码

.proitem{
  position: relative;
  &::after{
    content: '';
    height: 0;
    width: 0;
    position: absolute;
    left: -.2rem;
    top: 45%;
    margin-top: -.03rem;
    border-width: .1rem;
    border-style: solid;
    border-color:  transparent $color-white transparent transparent;
  }
}

关键点
border-color: transparent $color-white transparent transparent;
箭头朝哪,哪边的颜色就用你想要的显示出来就可以