php code not rendering bootstrap alert - php

Question

I'm fairly new to coding and have been struggling to get my contact_process.php form to display an alert message when the contact form's name or email is filled out incorrectly. For some reason, my .alert .alert-danger class does not display, but my .alert .alert-success class does after my form is submitted. I'm storing the results of my if else statement in the variable result and using echo to display it. Any help would be most appreciated.
Here's my code:
<?php
// isset function checks if the variable is set or has a value
if (isset($_POST['submit'])) {
// Declaring the variables
$name = $_POST['name'];
$email = $_POST['email'];
$date = $_POST['date'];
$message = $_POST['message'];
$from = 'Business Name';
$to = 'byron#gmail.com';
$subject = 'New Contact';
// Fills the content of the email
$body = "From: $name\n Email: $email\n DOB: $date\n Message:\n $message";
// Checks that the user entered a name
if (!$_POST['name']) {
$errorName = 'Enter your first and last name please';
}
// Checks if the user entered a valid email address
if (!$_POST['email'] || !filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) {
$errorEmail = 'Only valid email addresses please';
}
// Function checks for errors, if there are none, it sends the form
if (!$errorName && !$errorEmail) {
if (mail ($to, $subject, $body, $from)) {
$result='<div class="alert alert-success" role="alert">Thank you for contacting our business.<br>We will contact you soon.</div>';
}
else {
$result='<div class="alert alert-danger" role="alert">Sorry your message was unsuccessful.<br>Please try again by returning to the contact page.</div>';
}
}
}
?>
<?php include 'header.php'; ?>
<main>
<!-- Echo prints the result of the form being sent or not -->
<?php echo $result; ?>
</main>
<?php include 'footer.php'; ?>