*{margin: 0;padding: 0;}

.big_box{
	width: 100%;
}

.big_box img{
	width: 100%;
	height: auto;
	display: block;
}

@media(max-width: 980px){
	.big_box{
		width: 100%;
	}
	
	.box{
		width: 100%;
		height: 100%;
	}
	
	.img_box{
		background-size: 100% 100%;
	}
}