IE issue with CSS used in .aspx (.NET) page

I purchased a template and I am trying to use it in a ASP.NET project. I am having some issues, especially with IE.

If you look at this page in IE you’ll see that the header background is misplaced and the textbox and “buscar” button do not show as they should. [URL=“”]Here is the HTML version of a similar page using the same CSS, it appears just fine. I guess somehow the .net interfers with the CSS but I can’t find what is the problem. Firefox or Chrome too do display the background fine but not the textbox and the “buscar” button.

Anyclue ?

Here are the differences: