.banner, .site_banner {
 margin: 0 auto;
 position: relative;
 overflow: hidden;
}
.banner .pic, .site_banner .pic{
 display: block;
 width: 100%;
	height: 456px;
}
.banner .pic img, .site_banner .pic img{
 width: 100%;
	height: 100%;
}

@media screen and (min-width: 769px) and (max-width: 1280px) {
.banner .pic, .site_banner .pic {
 height: 256px;
}
}
@media only screen and (max-width:768px) {
 .banner .pic, .site_banner .pic{
 width: 100%;
 height: auto;
 display:none;
 }
}