css 实现小箭头

<div class="trange"></div>

.trange{
        position: absolute;
        right: 10px;
        top: 40px;
        width: 10px;
        height: 10px;
        border:#666 solid;
        border-width: 1px 1px 0 0;
        transform: rotate(135deg);
        margin-bottom: 10px;
    }

• 下拉是135，上拉是315……