Which version of Asp.net provide Html5 form

Hi, have not being in touch with Aspnet for a while. Feel like a newbie again. Excuse me if I ask some stupid questions.
Specifically, I want to know :
understand Asp.net will return html back to Web Browser.
1. If I want to handle mobile phone like WinPhone, Android and iOS which handle Html5, which version of Asp.net I should use that return html5?
2. If the Aspnet webForm is Html5 Form?
3. How to detect Mobile browsers(iOS,WP,Android) and return the mobile  form size just fit the screen of the phone?
Thanks.