背景图命名错误修改

html/download/css/download.css

@@ -10,7 +10,7 @@ img {
	width: 100%;
	max-width: 640px;
	height: 100%;
	background-image: url(../images/BG.PNG);
	background-image: url(../images/BG.png);
	background-repeat: no-repeat;
	background-position: center top;
	background-size: cover;