body:before{
    content: 'at style_main';
}	

@media only screen and (device-width: 768px) { /* target=768px wide */
	body:before{
		content: 'at style_768';
	}	
}

@media only screen and (max-width: 479px) { /* target= mobile ~300 wide */
	body:before{
		content: 'at style_320';
	}
}

@media only screen and (max-width: 768px) { /* target= mobile 480 wide */

 	body:before{
    	content: 'at style_400';
  	}	
}	

@media only screen and (min-width:1024px ) { /* target=Desktop */

 	body:before{
    	content: 'at style_1024';
  	}
}