responsive image in asp.net/css

The problem is with the viewport of both the devices. You need to understand that a pixel is not a device pixel. Every browser on a (even a) single device has different algorithm to determine what is a pixel value. So, that is why you cannot claim to have a same layout on every device and every browser. 

 

This is one of the problems that occur in web designing. When you pull your hairs because the layout that works for one browser doesn't work for the second. As Manoj has said, you can also try using percentage values for width and other attributes. But that won't also help you.

 

What you need is different stylesheets for different screens. Or in other ways, you can use CSS3 media queries for different screens and different sizes. And render the website on different screens. Read about CSS3 media queries on MDN.