有关实现CSS二维码扫描的效果

扫描二维码的效果，我原以为不好写呢，后来想了想其实挺简单的，几行代码，走起

<p class="code-bg">
    <p class="line"></p>
</p>

.code-bg{
		    position: relative; 
		    height: 200px; width: 200px; 
		    margin: 0px auto;/*此处为了居中*/
		    background: url(img/ewm1.jpg) center top no-repeat; /*二维码*/
		}
		.line{ 
		    position: absolute; 
		    left: -80px; 
		    z-index: 2; 
		    height: 3px; width: 360px; 
		    background: url(img/share/dapai.png) no-repeat; /*上下扫的线*/
		    /*动画效果*/
		    animation: myScan 1s infinite alternate; 
		    -webkit-animation: myScan 1s infinite alternate; 
		}
		@keyframes  myScan{
		    from { top:0px; }
		    to { top: 197px; }
		}
		-webkit-@keyframes  myScan{
		    from { top:0px; }
		    to { top: 197px; }
		}