CSS and JS compression and combine in single webserver call

Hi All,
I am facing some performace problem in my we site.What I have is 10 css in app_theme folder.
When I FireBuged it show 10  different call to webserver.I want to reduce these calls to one.
I read many articles on Internet but maximum article says to place path of each CSS into web.config.
But i dont want to change the web.config ,is should automatically combine the css.
Is there any soultion for this.
 
Thank
Sachin
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