How to make a browser capabilities in asp.net? css code

Use CSS3's media queries for that. Media queries allow you to provide a different design for your web applications and then content based on the browser, device and the size of the viewport that user is previewing your application in. 

 

I think, you are looking forward to this feature. :-) 

 

For more, read this: https://developer.mozilla.org/en-US/docs/Web/CSS/Media_Queries/Using_media_queries