css 写 >箭头

.area-input {
      position: relative;

      .at-input__container::after {
        content: "";
        height: 18px;
        width: 18px;
        top: 36px;
        right: 30px;
        border-width: 2px 2px 0 0;
        border-color: #CCCCCC;
        border-style: solid;
        transform: matrix(0.71, 0.71, -0.71, 0.71, 0, 0);
        position: absolute;
      }
    }