Visual Studio (2012 and lower) deletes CSS properties

Question

I have a really strange problem with Visual Studio 2010. When I add CSS properties for a gradient to my stylesheet, Visual Studio is going to delete it after some times of d

Answer 1

Gradients are CSS3 Properties.

Visual Studio do not support CSS3 and HTML5 and that might be the problem here.
But there is support for HTML5 & CSS3 in Visual Studio 2010 SP1
So, why don't you download Visual Studio 2010 SP1 and try?