@import url("header.css");    
@import url("small.css") only screen and (max-width:575px);    
@import url("medium.css") only screen and (max-width:991px) and (min-width:576px);    
@import url("large.css") only screen and (min-width:992px);    
@import url("main.css");    
@import url("footer.css");