ASP .NET MVC How to increase the width of an inputfield with @Html.EditorFor

I just cant fix something that seems so easy.
I want a textbox (editorfor) for a model property and I would like to increase its width but nothing is happening. I’m using the code as listed below. I tried setting the width to 500px but nothing happens. Ideally I would like the textbox to stretch over the full width of the container. Any ideas?

Is Absolute positioning a best practice or should I avoid it?

I am watching the ASP.NET learn video on http://www.asp.net/learn/3.5-videos/video-13.aspx
and it is showing you can place controls on a page using Absolute positioning. I am just wondering if this is a best practice or should I avoid Absolute positioning? It seems like a nice, easy feature, but there must be some reason why it is not selected by default in the VS IDE.