I haven't got answer so I am updating this question
as per the reply from Mr. Seanrose the link should adjust on the mobile vieport but it doesnt, so is there any other link I should use for authantication on the mobile ?
I am developing the HTML5/javascript based mobile application for box. for getting the auth code I use following url https://www.box.com/api/oauth2/authorize?response_type=code&client_id=' + CLIENT_ID + '&state=authenticated'
but this is non mobile url hence the page is getting displayed very small. is there mobile specific URL for authentication ?
Thanks for the support