Styled dropdown with Multiple options generated checkboxes are not Styled

[rohan210]

<select name="X" multiple>
<option value="x1">X1</option>
<option value="x2">X2</option>
<option value="x3">X3</option>
<option value="x4">X4</option>
</select>

jQuery("select").transformSelect();

Then the generated checkboxes are not styled.