下拉列表框的怎么去掉边框啊
<select id="s0" name="so">
<option value="- please select your options -"> - please select your options -</option>
<option value="1">option1</option>
<option value="2">option2</option>
<option value="3">option3</option>
<option value="4">option4</option>
<option value="5">option5</option>
</select>
代码