<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Form Validation</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            background-color: #f0f2f5;
        }
        .container {
            max-width: 600px;
            margin: 50px auto;
            padding: 20px;
            background-color: white;
            border-radius: 8px;
            box-shadow: 0 2px 5px rgba(0,0,0,0.1);
        }
        .form-group {
            margin-bottom: 15px;
        }
        .form-group label {
            display: block;
            margin-bottom: 5px;
            font-weight: bold;
        }
        .form-group input {
            width: 100%;
            padding: 10px;
            border: 1px solid #ddd;
            border-radius: 5px;
            font-size: 1em;
        }
        .form-group input:invalid {
            border-color: red;
        }
        .form-group input:valid {
            border-color: green;
        }
        button {
            padding: 10px 20px;
            border: none;
            border-radius: 5px;
            background-color: #007bff;
            color: white;
            font-size: 1em;
            cursor: pointer;
        }
        button:hover {
            background-color: #0056b3;
        }
    </style>
</head>
<body>
    <div class="container">
        <h1>Form Validation</h1>
        <form>
            <div class="form-group">
                <label for="name">Name</label>
                <input type="text" id="name" required>
            </div>
            <div class="form-group">
                <label for="email">Email</label>
                <input type="email" id="email" required>
            </div>
            <div class="form-group">
                <label for="age">Age</label>
                <input type="number" id="age" min="1" max="120" required>
            </div>
            <button type="submit">Submit</button>
        </form>
    </div>
</body>
</html>