<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Light Flicker</title>
<style>
    /* Basic styling for the light */
    #light {
        width: 100px;
        height: 100px;
        background-color: green;
        border-radius: 50%;
        animation: flicker 0.5s infinite alternate; /* Animation to flicker the light */
    }

    /* Keyframes for flicker animation */
    @keyframes flicker {
        0% { opacity: 1; }
        50% { opacity: 0.5; }
        100% { opacity: 1; }
    }
</style>
</head>
<body>

<!-- Light element -->
<div id="light"></div>

<script>
    // Function to toggle light color between red and green
    function toggleLightColor() {
        var light = document.getElementById('light');
        if (light.style.backgroundColor === 'green') {
            light.style.backgroundColor = 'red';
        } else {
            light.style.backgroundColor = 'green';
        }
    }

    // Set interval to toggle light color every 2 seconds (2000 milliseconds)
    setInterval(toggleLightColor, 2000);
</script>

</body>
</html>