how can generate stream from 1 css file to multiple css files ?

Question

how can generate stream from 1 css file to multiple css files ?

I have 3 css files i want to change the value from 1.css to multiple files like 2.css , 3.css
in 1.css i want body and h tag will be work for IE8 
in 2.css i want this will for IE9
in 3.css i want this will for mozila and so on..
 i am using winform application also i have editor then generate the source code 

so tell me how can i do this ????
1.css

body

{

    border-right: thin groove;

    border-top: thin groove;

    border-left: thin groove;

    color: blue;

    border-bottom: thin groove;

    font-family: Tahoma, Trebuchet MS;

}

h1

{

color:red;

background-color:Yellow;

font-family:Comic Sans MS;

}

2.css

h2

{

color: Gray ;

background-color: Blue ;

font-family: Arial Unicode MS ;

}

3.css

h2

{

color:Blue;

background-color:Green;

font-family: Berlin Sans FB Demi ;

}