CSS styles rendering differently in .Net

This is more of a curiosity question than anything else but if anyone has a suggestion as to what I'm doing incorrectly, if anything, it would be great.

I am using drag and drop ui with objects that are very CSS intensive. I usually create the objects in an html page, apply the html structure, styles, images, etc... until I have the complete object. Then I copy the styles to the .css file and the html images etc.. to their respective directories.

When I run the .Net solution the objects render completely out of whack from what looked real nice in the html page. Then I need to clean it up and change the styling so the objects loo开发者_如何学运维k correct in the .aspx/.ascx pages.

I've noticed this behavior in IE8 and IE9. Why does the .css render differently?

Thanks.

IE has many, many well-known CSS quirks, and the ASP.NET development environment uses IE8's rendering engine. So, the solution is to code cross-browser-compatibly.