<html>
<head>
    <meta charset="utf-8">
    <title>Scroll Down Animation</title>
    <link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
    <div class="center">
        <div class="arrow"></div>
    </div>
</body>
</html>
body
{
    margin: 0;
    padding: 0;
    background: #0079a5;
}
.center
{
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%);
    width: 0;
    height: 160px;
    border-left: 6px dashed rgba(255,255,255,.1);
}
.arrow
{
    position: absolute;
    top: 0;
    left: -6px;
    height: 40px;
    width: 6px;
    background: #fff;
    animation: animate 2s infinite;
}
.arrow:before
{
    content: '';
    position: absolute;
    bottom: 0;
    left: -10px;
    width: 20px;
    height: 20px;
    border-bottom: 6px solid #fff;
    border-right: 6px solid #fff;
    transform: rotate(45deg);
}
@keyframes animate
{
    0%
    {
        transform: translateY(0);
        opacity: 0.5;
    }
    50%
    {
        transform: translateY(80px);
        opacity: 1;
    }
    100%
    {
        transform: translateY(160px);
        opacity: 0;
    }
}

External CSS

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External JavaScript

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