移动端屏幕尺寸

/*智能手机*/
@media screen and (max-width:480px) {
	footer img {
		width: 20%;
	}
}
/*竖屏平板*/
@media screen and (max-width:768px) and (min-width:480px) {
	footer img {
		width: 15%;
	}
}
/*横屏平板*/
@media screen and (max-width:1024px) and (min-width:768px) {
	footer img {
		width: 10%;
	}
}
/*pc*/
@media screen and (min-width:1024px) {
	footer img {
		width: 6%;
	}
}