#picsWindow>img {
	position: absolute; top: 0px; left:0px; 
	opacity: 0;
	transition: all 2s linear;
	width: 1920px;
	height: 1080px;
	border-radius: 18px;
}
#picsWindow>img.show {
	opacity: 1; 
	z-index: 10;   /* 否则是最底下一张  btn点击 alert alt*/
}