select下拉框箭头样式修改

<style>
/*下拉前箭头*/
    select{
        /*取消默认箭头开始*/
        appearance:none;
        -moz-appearance:none;
        -webkit-appearance:none;
        /*取消默认箭头结束*/
        border: none;
        width: 9rem;
        font-size: 1rem;
        color: #666;
        text-align-last: center; /* 文本居中*/
        background: url(style/jiantou.png) no-repeat right 0.5rem center;
        background-size: 0.45rem 0.8rem;
    }
/*下拉后箭头*/
    select:focus {
        background: url(style/jiantou_bottom.png) no-repeat right 0.5rem center;
        background-size: 0.8rem 0.45rem;
    }
    /*修改option*/
    option::-ms-expand{ display: none; }
  option{
      -moz-appearance:none; /* Firefox */
      -webkit-appearance:none; /* Safari 和 Chrome */
      appearance:none;
  }
  /* --背景色字体颜色--*/
  option:hover{
      color:#fff;
      background-color:#1E90FF;
  }
</style>