Need help in responsive textbox

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VB

ASP.NET

Sir, i have a form in which i am showing 3-4 textbox and 1 submit button. i want to make this form mobile friendly also. i want to show my textbox in center or from with 40% width but when open this form on mobile it fit to the mobile screen like "m.facebook.com" login page.

What I have tried:

i am trying some diffrents codes:

    <meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1" />

and using bootstrap css:

<asp:TextBox ID="firstname" runat="server"  CssClass="form-control" placeholder="Name Of the Client" />

but its not working for me.