选择元素箭头图像在选择时消失

Question

我使用以下代码创建自定义（到度）下拉框（选择）元素

直到我点击下拉菜单然后箭头消失

css和html如下：

.styled_select {
	   width: 200px;
	   height: 34px;
	   overflow: hidden;
	   background: url(/images_/icons/down_arrow_select.jpg) no-repeat right #ddd;
	}

	select {
	   background: transparent;
	   width: 233px;
	   height:34px;
	   padding: 5px;
	   -webkit-appearance: none;
	   color:#666;
	   border:none;
	   cursor:pointer;
	}

 <div class="styled_select">
    <select name="reason">
	  <option value=1>1</option>
	  <option value=2>2</option>
	  <option value=3>3</option>
	  <option value=4>4</option>
	</select>
  </div>