PHP filter_input_array() | Bulk Data Filtering

<form method="post" action="process.php">
    <label for="email">Email:</label>
    <input type="text" id="email" name="email" placeholder="example@address.com">
    <br>
    <label for="age">Age (1-120):</label>
    <input type="text" id="age" name="age" placeholder="Enter years">
    <br>
    <input class="btn-submit" type="submit" value="Submit">
</form>

form {
    max-width: 400px;
    padding: 20px;
    border: 1px solid #ddd;
    border-radius: 8px;
    font-family: sans-serif;
}

h3 {
    margin-top: 0;
    color: #333;
}

label {
    display: block;
    margin-bottom: 5px;
    font-weight: bold;
    color: #555;
}

input[type="text"] {
    width: 100%;
    padding: 10px;
    margin-bottom: 15px;
    border: 1px solid #ccc;
    border-radius: 4px;
    box-sizing: border-box; /* Prevent expansion over the edge */
}

.btn-submit {
    background-color: #28a745;
    color: white;
    padding: 10px 15px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    width: 100%;
    font-size: 16px;
}

.btn-submit:hover {
    background-color: #218838;
}

<?php
/**
 * Bulk validation using filter_input_array
 */
if ($_SERVER["REQUEST_METHOD"] === "POST") {
    // Definition of rules for each field individually
    $filters = [
        'email' => FILTER_VALIDATE_EMAIL,
        'age' => [
            'filter' => FILTER_VALIDATE_INT,
            'options' => [
                'min_range' => 1,
                'max_range' => 120
            ]
        ]
    ];

    // Execution of filtering for all fields at once
    $inputs = filter_input_array(INPUT_POST, $filters);

    echo "<h3>Processing Results:</h3>";

    if ($inputs) {
        // Email validation
        if ($inputs['email'] === false) {
            echo "<p style='color: red;'>Email address is not valid.</p>";
        } elseif ($inputs['email'] === null) {
            echo "<p style='color: orange;'>Email field is missing.</p>";
        } else {
            echo "<p style='color: green;'>Email is okay: " . htmlspecialchars($inputs['email']) . "</p>";
        }

        // Age validation
        if ($inputs['age'] === false) {
            echo "<p style='color: red;'>Age must be a number between 1 and 120.</p>";
        } elseif ($inputs['age'] === null) {
            echo "<p style='color: orange;'>Age field is missing.</p>";
        } else {
            echo "<p style='color: green;'>Age is okay: " . htmlspecialchars($inputs['age']) . "</p>";
        }
    } else {
        echo "<p style='color: red;'>A system error occurred during filtering.</p>";
    }
}
?>

Working with the filter_input_array() function