How to show dropdown outside the scroll content section with help of CSS property in Salesforce?

Hi,

Please take reference from the following code

<select name='menu'>
<option value='1'>first item</option>
<option value='2'>second item</option>
<option value='3'>third item</option>
<option value='4'>fourth item</option>
<option value='5'>fifth item</option>
<option>........
<option>........
//I have many options.....
</select>

select {
height:50px;
overflow-y: scroll;
}