<!DOCTYPE html>
<html>
<head>
<title>Date of Birth Calculator</title>
<style type="text/css">
label, input, button {
display: block;
margin: 10px;
}
</style>
</head>
<body>
<h1>Date of Birth Calculator</h1>
<label for="birthdate">Enter your birthdate:</label>
<input type="date" id="birthdate">
<button onclick="calculateAge()">Calculate Age</button>
<p id="result"></p>
<script type="text/javascript">
function calculateAge() {
var birthdate = new Date(document.getElementById("birthdate").value);
var today = new Date();
var age = Math.floor((today - birthdate) / (365.25 * 24 * 60 * 60 * 1000));
document.getElementById("result").innerHTML = "Your age is: " + age;
}
</script>
</body>
</html>