The outer layer sets a layer of div to cover the selected border and drop-down arrow (spoof display effect)
1 <div style="width:80px;height:30px;margin:-4px;"> 2 <select style="width:120px;float:left;font-size:20px;"> 3 <option>1</option> 4 <option>2</option> 5 </select> 6 <div>