> In this design, we use a text field for day, month and year. So far this has tested well, with the main issue being that some people pause and wonder whether to include a leading zero (for example '01' ).
Or just allow both versions (01 or 1). Edit: this works best if the form is validated client-side, otherwise you still get people wondering what is allowed in the field because there is no immediate response to input.
Just put it in the example below...