<div style="width:100px;overflow:hidden;position:relative;background:red;">
<select id="aa" style="width:100px;position:absolute;left:0;top:1px;clip:rect(1px auto auto 81px);" onchange="this.nextSibling.value=this[this.selectedIndex].innerText" >
<option value="aa">aa1</option>
<option value="bb">bb1</option>
<option value="cc">cc1</option>
</select><input name="dd" type="text" id="dd" style="width:100px; " />
</div>