I have configured Twitter Bootstrap with my Asp.net MVC 3 application.But when I look at the bootstrap.css It’s having lot of syntax issues like shown below.
I am using Visual studio 2010 with CSS 3 enabled.
Error List 1:

Error List 2 :

Error List 3 :

UPDATE
Folder structure after adding Bootstrap into my MVC project is as below.

How to get rid of above issues ?
The problem you’ve encountered stems from the fact that VS2010 has buggy CSS intellisense. Viewing the bootstrap.css file in VS2012 is much improved, having far fewer parse errors reported. Neither of these 2 parsers are necessarily an indication that the CSS in invalid though. Deciding upon and then testing bootstrap-specific style rules across your target browsers and platforms is a far stronger indicator of the validity of those style rules. You should run your CSS through an external validator, such as mentioned by @kolin, if you’re concerned about whether it’s valid. The ultimate test is always how it renders across browsers.