diff --git a/source/_daily_emails/2022-08-12.md b/source/_daily_emails/2022-08-12.md
index c235f8b2..d9014b2a 100644
--- a/source/_daily_emails/2022-08-12.md
+++ b/source/_daily_emails/2022-08-12.md
@@ -64,7 +64,7 @@ You can also use the `COMPOSE_PROJECT_NAME` variable inside Docker Compose files
 
 For example, if you use Traefik and needed to override the host URL for a service, the string will be interpolated and the project name would be injected as you'd expect.
 
-```yaml
+```language-yaml
 labels:
     - "traefik.http.routers.${COMPOSE_PROJECT_NAME}.rule=Host(
         `${COMPOSE_PROJECT_NAME}.docker.localhost`,
diff --git a/source/_daily_emails/2022-08-15.md b/source/_daily_emails/2022-08-15.md
index 6d2435d3..cd61eb99 100644
--- a/source/_daily_emails/2022-08-15.md
+++ b/source/_daily_emails/2022-08-15.md
@@ -15,7 +15,7 @@ A Makefile contains a number of named targets that you can reference, and each h
 
 For example:
 
-```yaml
+```language-language-yaml
 # Start the project.
 start:
 	docker-compose up -d
diff --git a/source/_daily_emails/2022-09-03.md b/source/_daily_emails/2022-09-03.md
index 479cec25..89980d05 100644
--- a/source/_daily_emails/2022-09-03.md
+++ b/source/_daily_emails/2022-09-03.md
@@ -15,7 +15,7 @@ By using one of these tools, you can programatically provision a new, blank serv
 
 For example, to [create a DigitalOcean droplet](https://docs.ansible.com/ansible/latest/collections/community/digitalocean/digital_ocean_module.htm):
 
-```yaml
+```language-yaml
 ---
 - community.digitalocean.digital_ocean_droplet:
     image: ubuntu-20-04-x64
@@ -35,7 +35,7 @@ If you needed to create a separate database server or another server for a new e
 
 [Creating an Amazon EC2 instance](https://docs.ansible.com/ansible/latest/collections/amazon/aws/ec2_instance_module.html#ansible-collections-amazon-aws-ec2-instance-module) looks very similar:
 
-```yaml
+```language-yaml
 ---
 - amazon.aws.ec2_instance:
     image_id: ami-123456
diff --git a/source/_daily_emails/2022-09-14.md b/source/_daily_emails/2022-09-14.md
index 617b9cb8..bc6f6802 100644
--- a/source/_daily_emails/2022-09-14.md
+++ b/source/_daily_emails/2022-09-14.md
@@ -10,7 +10,7 @@ I cloned a fresh version of my [Docker Examples repository](https://github.com/o
 
 I ran `mkdir -p web/modules/custom/example/tests/src/Functional` to create the directory structure that I needed, and then `touch web/modules/custom/example/tests/src/Functional/ExampleTest.php` to create a new test file and populated it with some initial code:
 
-```php
+```language-php
 <?php
 
 namespace Drupal\Tests\example\Functional;
@@ -27,7 +27,7 @@ class ExampleTest extends BrowserTestBase {
 
 For the simplest test, I decided to test some existing Drupal core functionality - that an anonymous user can view the front page:
 
-```php
+```language-php
 /** @test */
 public function the_front_page_loads_for_anonymous_users() {
   $this->drupalGet('<front>');
@@ -42,7 +42,7 @@ As this is existing functionalty, the test passes. I can change either the path
 
 With the first test working, it's easy to add more for other functionality, such as whether different users should be able to access administration pages:
 
-```php
+```language-php
 /** @test */
 public function the_admin_page_is_not_accessible_to_anonymous_users() {
   $this->drupalGet('admin');
diff --git a/source/_daily_emails/2022-09-16.md b/source/_daily_emails/2022-09-16.md
index 4048b26a..c071cff5 100644
--- a/source/_daily_emails/2022-09-16.md
+++ b/source/_daily_emails/2022-09-16.md
@@ -15,7 +15,7 @@ I find that these higher-level types of tests are easier and quicker to set up c
 
 For example, this `Device` class which is a data transfer object around Drupal's `NodeInterface`. It ensures that the correct type of node is provided, and includes a named constructor and a helper method to retrieve a device's asset ID from a field:
 
-```php
+```language-php
 final class Device {
 
   private NodeInterface $node;
@@ -47,7 +47,7 @@ I need to specify what value is returned from the `bundle()` method as well as g
 
 I need to mock the `get()` method and specify the field name that I'm getting the value for, which also returns it's own mock for `FieldItemListInterface` with a value set for the `getString()` method.
 
-```php
+```language-php
 /** @test */
 public function should_return_an_asset_id(): void {
   // Arrange.
@@ -84,7 +84,7 @@ If I was to refactor from using the `get()` and `getString()` methods to a diffe
 
 This is how I could write the same test using a kernel (integration) test:
 
-```php
+```language-php
 /** @test */
 public function should_return_an_asset_id(): void {
   // Arrange.
diff --git a/source/_daily_emails/2022-10-03.md b/source/_daily_emails/2022-10-03.md
index 82be5b65..64cef973 100644
--- a/source/_daily_emails/2022-10-03.md
+++ b/source/_daily_emails/2022-10-03.md
@@ -8,7 +8,7 @@ tags: [php]
 
 Here's a snippet of some Drupal code that I wrote last week. It's responsible for converting an array of nodes into a Collection of one of it's field values.
 
-```php
+```language-php
 return Collection::make($stationNodes)
   ->map(fn (NodeInterface $station): string => $station->get('field_station_code')->getString())
   ->values();
@@ -28,7 +28,7 @@ It accepts the original node but checks to ensure that the node is the correct t
 
 I've added a helper method to get the field value, encapsulating that logic in a reusable function whilst making the code easier to read and its intent clearer.
 
-```php
+```language-php
 namespace Drupal\mymodule\ValueObject;
 
 use Drupal\node\NodeInterface;
@@ -60,7 +60,7 @@ final class Station implements StationInterface {
 
 This is what my code now looks like:
 
-```php
+```language-php
 return Collection::make($stationNodes)
   ->map(fn (NodeInterface $node): StationInterface => Station::fromNode($node))
   ->map(fn (StationInterface $station): string => $station->getStationCode())
diff --git a/source/_daily_emails/2022-10-09.md b/source/_daily_emails/2022-10-09.md
index 8be3f91d..21eb447d 100644
--- a/source/_daily_emails/2022-10-09.md
+++ b/source/_daily_emails/2022-10-09.md
@@ -37,7 +37,7 @@ It also makes it more obvious to anyone reading the code that these values are b
 
 It's similar to having this example PHP code:
 
-```php
+```language-php
 function __invoke(string $type, int $limit): void {};
 ```
 
diff --git a/source/_daily_emails/2022-11-14.md b/source/_daily_emails/2022-11-14.md
index ceb21c10..6fc0b0b7 100644
--- a/source/_daily_emails/2022-11-14.md
+++ b/source/_daily_emails/2022-11-14.md
@@ -10,7 +10,7 @@ tags:
 
 When writing object-orientated code, particularly in PHP, you usually write method names using camel-case letters - such as:
 
-```php
+```language-php
 public function doSomething(): void {
   // ...
 }
@@ -18,7 +18,7 @@ public function doSomething(): void {
 
 This is also true when writing methods within a test class - only that the method name is prefixed with the word `test`:
 
-```php
+```language-php
 public function testSomething(): void {
 }
 ```
@@ -27,7 +27,7 @@ This is probably expected and complies with the PSR code style standards like PS
 
 Something that I've seen some PHP developers and some frameworks prefer is to write their test methods using snake-case letters and  commonly removing the `test` prefix in favour of using an annotation:
 
-```php
+```language-php
 /** @test */
 public function the_api_should_return_a_200_response_code_if_everything_is_ok(): void {
   // ...
diff --git a/source/_daily_emails/2022-12-08.md b/source/_daily_emails/2022-12-08.md
index 38182ae5..e0438e3e 100644
--- a/source/_daily_emails/2022-12-08.md
+++ b/source/_daily_emails/2022-12-08.md
@@ -14,7 +14,7 @@ As long as a class implements an Interface, it can be decorated.
 
 For example, if I have this PHP interface:
 
-```php
+```language-php
 interface DoesSomething
 {
     public function doSomething(): void;
@@ -23,7 +23,7 @@ interface DoesSomething
 
 I could have this class that does something:
 
-```php
+```language-php
 final class FirstClass implements DoesSomething
 {
     public function doSomething(): void
@@ -37,7 +37,7 @@ If I need to do something else, like caching or logging the result, I can decora
 
 To do this, I need another class that implements the same interface and inject the original version.
 
-```php
+```language-php
 final class SecondClass implements DoesSomething
 {
     public function __constuct(
diff --git a/source/_daily_emails/2022-12-10.md b/source/_daily_emails/2022-12-10.md
index 13f74b37..59d39438 100644
--- a/source/_daily_emails/2022-12-10.md
+++ b/source/_daily_emails/2022-12-10.md
@@ -19,7 +19,7 @@ A local port needs to be exposed from the database container that Neovim can con
 
 I usually do this with a `docker-compose.override.yaml` file:
 
-```yaml
+```language-yaml
 services:
   database:
     ports:
diff --git a/source/_daily_emails/2023-04-11.md b/source/_daily_emails/2023-04-11.md
index 1a891ba8..4f70ae6d 100644
--- a/source/_daily_emails/2023-04-11.md
+++ b/source/_daily_emails/2023-04-11.md
@@ -45,7 +45,7 @@ Now I can run `make composer COMPOSER_ARGS="info drupal/core"` and see what I wa
 
 `just`, on the other hand, allows for defining parameters to its recipes: 
 
-```yaml
+```language-yaml
 composer *args:
   docker compose exec php composer {{ args }}
 ```
diff --git a/source/_daily_emails/2023-04-12.md b/source/_daily_emails/2023-04-12.md
index 97e94c78..f0734105 100644
--- a/source/_daily_emails/2023-04-12.md
+++ b/source/_daily_emails/2023-04-12.md
@@ -14,7 +14,7 @@ If I'm passing arguments into a constructor, I can declare a visibility and it w
 
 Here's an example of a value of a data transfer object that accepts a sort code and account number as strings:
 
-```php
+```language-php
 class AccountDetails {
 
   public function __construct(
@@ -27,7 +27,7 @@ class AccountDetails {
 
 Without promoted constructor properties, I'd need to create the properties and assign them manually, and I'd have this:
 
-```php
+```language-php
 class AccountDetails {
 
   public string $accountNumber;
diff --git a/source/_daily_emails/2023-04-13.md b/source/_daily_emails/2023-04-13.md
index 8b30337d..bb33c79f 100644
--- a/source/_daily_emails/2023-04-13.md
+++ b/source/_daily_emails/2023-04-13.md
@@ -10,7 +10,7 @@ tags:
 
 Continuing with yesterday's data transfer object (DTO) example, something that can be done since PHP 8.1 is to make properties read-only:
 
-```php
+```language-php
 class AccountDetails {
 
   public function __construct(
@@ -25,7 +25,7 @@ This means the public properties can be read and used without the need for gette
 
 Without `readonly`, a DTO can be created and the property values can be changed:
 
-```php
+```language-php
 $accountDetails = new AccountDetails('12345678', '00-00-00');
 $accountDetails->accountNumber = 'banana';
 ```
diff --git a/source/_daily_emails/2023-04-14.md b/source/_daily_emails/2023-04-14.md
index 11097ea9..9e177885 100644
--- a/source/_daily_emails/2023-04-14.md
+++ b/source/_daily_emails/2023-04-14.md
@@ -13,7 +13,7 @@ A data transfer object only stores data but we could also use a value object tha
 
 For example, we could validate that the account number is the correct length and the sort code is the correct format:
 
-```php
+```language-php
 class AccountDetails {
 
   public function __construct(
diff --git a/source/_daily_emails/2023-04-16.md b/source/_daily_emails/2023-04-16.md
index deebce36..2d3225fe 100644
--- a/source/_daily_emails/2023-04-16.md
+++ b/source/_daily_emails/2023-04-16.md
@@ -12,7 +12,7 @@ Marian Kostadinov ([stochnagara on Twitter](https://twitter.com/stochnagara)) re
 
 Looking at the previous class:
 
-```php
+```language-php
 class AccountDetails {
 
   public function __construct(
@@ -25,7 +25,7 @@ class AccountDetails {
 
 Instead of setting each property as `readonly`, the whole class can instead be marked as `readonly`:
 
-```php
+```language-php
 readonly class AccountDetails {
 
   public function __construct(
diff --git a/source/_daily_emails/2023-04-19.md b/source/_daily_emails/2023-04-19.md
index e8c05047..b57585f8 100644
--- a/source/_daily_emails/2023-04-19.md
+++ b/source/_daily_emails/2023-04-19.md
@@ -17,7 +17,7 @@ Why? I didn't like the inconsistency of using one approach for variable names an
 
 I'd have had code like this with a mixture of both:
 
-```php
+```language-php
 class MyClass {
 
   private EntityTypeManagerInterface $entityTypeManager;
@@ -31,7 +31,7 @@ class MyClass {
 
 Or even more simply:
 
-```php
+```language-php
 $entity_type_manager = \Drupal::entityTypeManager();
 ```
 
diff --git a/source/_daily_emails/2023-04-23.md b/source/_daily_emails/2023-04-23.md
index 86614a85..3b115cef 100644
--- a/source/_daily_emails/2023-04-23.md
+++ b/source/_daily_emails/2023-04-23.md
@@ -13,7 +13,7 @@ I've seen a lot on social media and posts and videos recently about Laravel Pipe
 
 This is an example from the new documentation:
 
-```php
+```language-php
 $user = Pipeline::send($user)
     ->through([
         GenerateProfilePhoto::class,
diff --git a/source/_daily_emails/2023-04-26.md b/source/_daily_emails/2023-04-26.md
index 738134e8..fa8c0d31 100644
--- a/source/_daily_emails/2023-04-26.md
+++ b/source/_daily_emails/2023-04-26.md
@@ -21,7 +21,7 @@ Maybe a user was pending initially, and they're active after running a command o
 
 To help me get started, I'll sometimes write a test like this with placeholders to separate the test into its separate stages:
 
-```php
+```language-php
 /** @test */
 function should_activate_a_pending_user(): void {
   // Arrange.
@@ -38,7 +38,7 @@ This makes me think about the different stages and what each might need to conta
 
 Or I might write it out in the "Given, When, Then" format:
 
-```php
+```language-php
 /** @test */
 function should_activate_a_pending_user(): void {
   // Given I have a user.
diff --git a/source/_daily_emails/2023-05-17.md b/source/_daily_emails/2023-05-17.md
index 4845b09d..412859f6 100644
--- a/source/_daily_emails/2023-05-17.md
+++ b/source/_daily_emails/2023-05-17.md
@@ -16,7 +16,7 @@ For example, the `drupal_set_message()` function was deprecated in Drupal 8.5 an
 
 Once it was deprecated, the function was changed to use the new service to avoid duplicating code and a message was added to notify Developers:
 
-```php
+```language-php
 function drupal_set_message($message = NULL, $type = 'status', $repeat = FALSE) {
   @trigger_error('drupal_set_message() is deprecated in Drupal 8.5.0 and will be removed before Drupal 9.0.0. Use \Drupal\Core\Messenger\MessengerInterface::addMessage() instead. See https://www.drupal.org/node/2774931', E_USER_DEPRECATED);
 
diff --git a/source/_daily_emails/2023-07-03.md b/source/_daily_emails/2023-07-03.md
index a8fb239c..d0d1b13f 100644
--- a/source/_daily_emails/2023-07-03.md
+++ b/source/_daily_emails/2023-07-03.md
@@ -18,7 +18,7 @@ I'm using PHPUnit's native assertions to check it returns a Collection (I regula
 
 My initial implementation was to loop over each node and use `assertSame` on its bundle before refactoring to create an array of unique bundle names and comparing it to my expected names:
 
-```php
+```language-php
 self::assertSame(
   expected: [$nodeType],
   actual: $haystack
diff --git a/source/_daily_emails/2023-08-17.md b/source/_daily_emails/2023-08-17.md
index 32437e41..c5110578 100644
--- a/source/_daily_emails/2023-08-17.md
+++ b/source/_daily_emails/2023-08-17.md
@@ -13,7 +13,7 @@ Writing custom assertions is a great way to clean up your test code.
 
 Here's an example from one of my client Drupal projects:
 
-```php
+```language-php
 private static function assertProductVariationHasPrice(ProductVariationInterface $productVariation, string $expectedPrice): void {
   self::assertSame(
     actual: $productVariation->getPrice()->getNumber(),
diff --git a/source/_daily_emails/2023-08-19.md b/source/_daily_emails/2023-08-19.md
index 3668c5c6..c312fa1e 100644
--- a/source/_daily_emails/2023-08-19.md
+++ b/source/_daily_emails/2023-08-19.md
@@ -14,7 +14,7 @@ In PHP, this is done by throwing an Exception if a condition is met.
 
 For example:
 
-```php
+```language-php
 if (!is_array(false)) {
   throw new \Exception('Not an array');
 }
@@ -22,13 +22,13 @@ if (!is_array(false)) {
 
 There's also the `assert` construct which, since PHP 8.0, throws an Exception by default:
 
-```php
+```language-php
 assert(is_array(false));
 ```
 
 You can also use an assertion library, such as `webmozart/assert` or `beberlei/assert` which provide assertions and guard methods:
 
-```php
+```language-php
 use Webmozart\Assert\Assert;
 
 Assert::isArray(false);
diff --git a/source/_daily_emails/2023-08-20.md b/source/_daily_emails/2023-08-20.md
index 10ec3b12..b68d8d43 100644
--- a/source/_daily_emails/2023-08-20.md
+++ b/source/_daily_emails/2023-08-20.md
@@ -12,7 +12,7 @@ Following yesterday's email about input validation, guard clauses and assertion
 
 For example:
 
-```php
+```language-php
 function createJourney(string $from, string $to, int $duration): void {
   var_dump($from, $to, $duration);
 }
@@ -22,13 +22,13 @@ In this code, each parameter has a type, but there's no validation on the values
 
 If I run this:
 
-```plain
+```language-plain
 createJourney('', '', -10);
 ```
 
 I would get this output:
 
-```plain
+```language-plain
 string(0) ""
 string(0) ""
 int(-10)
@@ -44,7 +44,7 @@ I can use an assertion library or throw my own Exceptions if the values pass the
 
 For example:
 
-```php
+```language-php
 function createJourney(string $from, string $to, int $duration): void {
   Assert::stringNotEmpty($from);
   Assert::stringNotEmpty($to);
diff --git a/source/_daily_emails/2023-09-07.md b/source/_daily_emails/2023-09-07.md
index abf90930..d0cf64f6 100644
--- a/source/_daily_emails/2023-09-07.md
+++ b/source/_daily_emails/2023-09-07.md
@@ -26,7 +26,7 @@ To start, we wrote a test for existing functionality within Drupal core - anonym
 
 This is the whole test:
 
-```php
+```language-php
 <?php
 
 namespace Drupal\Tests\my_module\Functional;
diff --git a/source/_daily_emails/2023-09-11.md b/source/_daily_emails/2023-09-11.md
index f6c078bb..eb059f66 100644
--- a/source/_daily_emails/2023-09-11.md
+++ b/source/_daily_emails/2023-09-11.md
@@ -18,7 +18,7 @@ If I look at some code, I want to see as few indentation levels as possible, mak
 Instead, you check for a condition; if that isn't met, you return early.
 For example, here is some code I saw recently during a meetup talk:
 
-```php
+```language-php
 $callingClass = $scope->getClassReflection()->getName();
 
 if ($callingClass === TextMessageQueueProcessor::class) {
diff --git a/source/_daily_emails/2023-10-02.md b/source/_daily_emails/2023-10-02.md
index 86c1ba43..4da28fd9 100644
--- a/source/_daily_emails/2023-10-02.md
+++ b/source/_daily_emails/2023-10-02.md
@@ -23,7 +23,7 @@ Only write comments that add value, and if there are fewer comments, they are ea
 
 This is an example from an open source pull request:
 
-```php
+```language-php
 /**
  * An interface for field access override.
  */
diff --git a/source/_daily_emails/2023-10-10.md b/source/_daily_emails/2023-10-10.md
index 81f49346..c20c490f 100644
--- a/source/_daily_emails/2023-10-10.md
+++ b/source/_daily_emails/2023-10-10.md
@@ -38,7 +38,7 @@ For example, to install Pathauto, you run `composer require drupal/pathauto`.
 
 Within its output, you'll see this:
 
-```plain
+```language-plain
 Package operations: 3 installs, 0 updates, 0 removals
   - Downloading drupal/token (1.12.0)
   - Downloading drupal/ctools (4.0.4)
diff --git a/source/_daily_emails/2023-11-16.md b/source/_daily_emails/2023-11-16.md
index 94ddeb08..65a9ed9e 100644
--- a/source/_daily_emails/2023-11-16.md
+++ b/source/_daily_emails/2023-11-16.md
@@ -16,7 +16,7 @@ Here's an example (thanks, ChatGPT, for the code).
 
 ## The Class to be tested (MyClass.php)
 
-```php
+```language-php
 <?php
 
 class MyClass {
@@ -36,7 +36,7 @@ class MyClass {
 
 ## Dependency Interface (DependencyInterface.php)
 
-```php
+```language-php
 <?php
 
 interface DependencyInterface {
@@ -48,7 +48,7 @@ interface DependencyInterface {
 
 ## A test class that ends up testing mocks (MyClassTest.php)
 
-```php
+```language-php
 <?php
 
 use PHPUnit\Framework\TestCase;
diff --git a/source/_daily_emails/2023-11-18.md b/source/_daily_emails/2023-11-18.md
index a424ba0f..59839dd2 100644
--- a/source/_daily_emails/2023-11-18.md
+++ b/source/_daily_emails/2023-11-18.md
@@ -16,7 +16,7 @@ In PHPUnit, there are different ways to write test methods.
 
 The standard way is to use camel-case method names with a `test` prefix, for example:
 
-```php
+```language-php
 public function testTheProjectNameShouldBeAString(): void
 {
     // ...
@@ -25,7 +25,7 @@ public function testTheProjectNameShouldBeAString(): void
 
 Another popular way, particularly in some frameworks, is to use snake-case method names:
 
-```php
+```language-php
 /** @test */
 public function the_project_name_should_be_a_string(): void
 {
diff --git a/source/_daily_emails/2023-11-26.md b/source/_daily_emails/2023-11-26.md
index c5722fe2..87aec28f 100644
--- a/source/_daily_emails/2023-11-26.md
+++ b/source/_daily_emails/2023-11-26.md
@@ -19,7 +19,7 @@ Unfortunately, they're often overused and are outdated compared to the code they
 
 For example, here's some PHP code:
 
-```php
+```language-php
 function sayHello(string $name, array $options = ['shout' => false]): void {
      echo 'Hello, ' . $name;
 }
@@ -53,7 +53,7 @@ Then you'll get this error:
 
 Now, we can use a docblock to provide more information to PHPStan to describe the structure of the `$options` array and that it has strings for keys and boolean values.
 
-```php
+```language-php
 /**
  * @param array<string, bool> $options
  */
@@ -61,7 +61,7 @@ Now, we can use a docblock to provide more information to PHPStan to describe th
 
 Although it's not erroring, we can add the `$name` parameter and declare it as a `string`.
 
-```php
+```language-php
 /**
  * @param string $name
  * @param array<string, bool> $options
@@ -78,7 +78,7 @@ We don't want an empty string for a name and want the correct options and values
 
 Let's change the docblock to this:
 
-```php
+```language-php
 /**
  * @param non-empty-string $name
  * @param array{shout: bool} $options
diff --git a/source/_daily_emails/2023-11-27.md b/source/_daily_emails/2023-11-27.md
index 500aa63f..28dc7748 100644
--- a/source/_daily_emails/2023-11-27.md
+++ b/source/_daily_emails/2023-11-27.md
@@ -16,7 +16,7 @@ As well as different base classes for types of tests - i.e. functional, kernel a
 
 For example, if we have this test:
 
-```php
+```language-php
 <?php
 
 namespace Drupal\Tests\example\Kernel;
@@ -62,7 +62,7 @@ When writing a lot of tests, this can result in duplication and more complex tes
 
 This can be simplified using `EntityKernelTestBase` instead of `KernelTestBase`:
 
-```php
+```language-php
 <?php
 
 use Drupal\KernelTests\Core\Entity\EntityKernelTestBase;
diff --git a/source/_daily_emails/2023-12-25.md b/source/_daily_emails/2023-12-25.md
index 010a5f0e..201624b4 100644
--- a/source/_daily_emails/2023-12-25.md
+++ b/source/_daily_emails/2023-12-25.md
@@ -41,7 +41,7 @@ Before adding tests, you must create a module to place them in.
 
 Run `mkdir -p web/modules/custom/atdc` to create an empty module directory, and create an `atdc.info.yml` file within it with this content:
 
-```yaml
+```language-yaml
 name: Example
 type: module
 core_version_requirement: ^10
@@ -58,7 +58,7 @@ Run `mkdir -p web/modules/custom/atdc/tests/src/Functional && touch web/modules/
 
 Then, add this content.
 
-```php
+```language-php
 <?php
 
 namespace Drupal\Tests\atdc\Functional;
@@ -77,7 +77,7 @@ Note: within a test class, the namespace is `Drupal\Tests\{module_name}` instead
 
 With the boilerplate class added, create a test method within it:
 
-```php
+```language-php
 public function testBasic(): void {
   self::assertTrue(FALSE);
 }
@@ -148,7 +148,7 @@ As you're writing functional tests by extending `BrowserTestBase`, you can make
 
 Replace the `testBasic` test method with the following:
 
-```php
+```language-php
 public function testFrontPage(): void {
   $this->drupalGet('/');
 
diff --git a/source/_daily_emails/2024-01-18.md b/source/_daily_emails/2024-01-18.md
index ea8c9345..baf7b791 100644
--- a/source/_daily_emails/2024-01-18.md
+++ b/source/_daily_emails/2024-01-18.md
@@ -15,7 +15,7 @@ In some instances, setting zero will return all items - essentially, an 'unlimit
 
 I imagine the code looks something like this:
 
-```php
+```language-php
 if ($limit > 0) {
   $query->range(0, $limit);
 }
@@ -31,7 +31,7 @@ It means the value could be either an integer or null, but I think the intent of
 
 This would make the code look like this:
 
-```php
+```language-php
 if (is_int($limit)) {
   $query->range(0, $limit);
 }
@@ -45,7 +45,7 @@ It wouldn't make sense to set a negative number as the limit or, as the unlimite
 
 This is the end code I'd likely write:
 
-```php
+```language-php
 if (is_int($limit)) {
   if ($limit < 1) {
     throw new InvalidArgumentException('A limit must be a positive integer.');
diff --git a/source/_daily_emails/2024-01-27.md b/source/_daily_emails/2024-01-27.md
index 7372c151..aa085c54 100644
--- a/source/_daily_emails/2024-01-27.md
+++ b/source/_daily_emails/2024-01-27.md
@@ -17,14 +17,14 @@ The default approach is that all files can be added, and you specify the files a
 
 For example, if my `.gitignore` file was this, these two directories would be ignored:
 
-```plain
+```language-plain
 vendor
 web
 ```
 
 The other approach is to ignore everything and unignore the things to add. For example:
 
-```plain
+```language-plain
 *
 !build.yaml
 !Dockerfile
diff --git a/source/_daily_emails/2024-01-28.md b/source/_daily_emails/2024-01-28.md
index 69e1325d..e4b004ad 100644
--- a/source/_daily_emails/2024-01-28.md
+++ b/source/_daily_emails/2024-01-28.md
@@ -27,7 +27,7 @@ Anything that affects multiple users - such as ignoring `vendor` or `node_module
 
 Add this to your `~/.gitconfig` or `~/.config/git/config` file to set the path for your global ignore file:
 
-```plain
+```language-plain
 [core]
   excludesFile = "~/.config/git/ignore"
 ```
diff --git a/source/_daily_emails/2024-02-08.md b/source/_daily_emails/2024-02-08.md
index 09dc6e74..0cb8385b 100644
--- a/source/_daily_emails/2024-02-08.md
+++ b/source/_daily_emails/2024-02-08.md
@@ -23,7 +23,7 @@ Going forward, I'd like to ensure that each Drupal module only uses its own clas
 
 Here's what I have so far for my [testing course codebase][atdc]:
 
-```php
+```language-php
 final class ArchitectureTest {
 
   public function test_classes_should_be_final(): Rule {
diff --git a/source/_layouts/base.html.twig b/source/_layouts/base.html.twig
index 3d564e31..abf7e477 100644
--- a/source/_layouts/base.html.twig
+++ b/source/_layouts/base.html.twig
@@ -37,8 +37,12 @@
         <meta property="twitter:title" content="{{ page.title }} | {{ site.name }}" />
       {% endif %}
     {% endblock %}
+
+    {% block styles %}{% endblock %}
   </head>
   <body>
     {% block body %}{% endblock %}
+
+    {% block scripts %}{% endblock %}
   </body>
 </html>
diff --git a/source/_layouts/page.html.twig b/source/_layouts/page.html.twig
index 3d01df5d..67aa7409 100644
--- a/source/_layouts/page.html.twig
+++ b/source/_layouts/page.html.twig
@@ -3,3 +3,20 @@
 {% block content_bottom %}
   {% include 'about-me.html.twig' %}
 {% endblock %}
+
+{% block styles %}
+<link rel="stylesheet" href="https://unpkg.com/@highlightjs/cdn-assets@11.9.0/styles/github-dark.min.css">
+
+<style type="text/css">
+.hljs {
+  background: transparent;
+}
+</style>
+{% endblock %}
+
+{% block scripts %}
+<script src="https://unpkg.com/@highlightjs/cdn-assets@11.9.0/highlight.min.js"></script>
+<script src="https://unpkg.com/@highlightjs/cdn-assets@11.9.0/languages/php.min.js"></script>
+
+<script>hljs.highlightAll();</script>
+{% endblock %}
diff --git a/source/_pages/atdc/1.md b/source/_pages/atdc/1.md
index c08ec471..dc5dab8b 100644
--- a/source/_pages/atdc/1.md
+++ b/source/_pages/atdc/1.md
@@ -30,7 +30,7 @@ Before adding tests, you must create a module to place them in.
 
 Run `mkdir -p web/modules/custom/atdc` to create an empty module directory and create an `atdc.info.yml` file within it with this content:
 
-```yaml
+```language-yaml
 name: ATDC
 type: module
 core_version_requirement: ^10
@@ -47,7 +47,7 @@ Run `mkdir -p web/modules/custom/atdc/tests/src/Functional && touch web/modules/
 
 Then, add this content.
 
-```php
+```language-php
 <?php
 
 namespace Drupal\Tests\atdc\Functional;
@@ -66,7 +66,7 @@ Note: within a test class, the namespace is `Drupal\Tests\{module_name}` instead
 
 With the boilerplate class added, create a test method within it:
 
-```php
+```language-php
 public function testBasic(): void {
   self::assertTrue(FALSE);
 }
@@ -137,7 +137,7 @@ As you're writing functional tests by extending `BrowserTestBase`, you can make
 
 Replace the `testBasic` test method with the following:
 
-```php
+```language-php
 public function testFrontPage(): void {
   $this->drupalGet('/');
 
diff --git a/source/_pages/atdc/10.md b/source/_pages/atdc/10.md
index b8f779a5..c497b1bf 100644
--- a/source/_pages/atdc/10.md
+++ b/source/_pages/atdc/10.md
@@ -18,7 +18,7 @@ Let's see how that would look as a unit test.
 
 Create a new test, `PostNodeRepositoryUnitTest` and, for now, just create a new `PostNodeRepository`:
 
-```php
+```language-php
 <?php
 
 // web/modules/custom/atdc/tests/src/Unit/PostNodeRepositoryUnitTest.php
@@ -43,7 +43,7 @@ But, as this is a unit test, you can't get the Repository from the service conta
 
 Try to fix this by creating a new `EntityTypeManager` and injecting it into the constructor:
 
-```php
+```language-php
 $repository = new PostNodeRepository(
   new EntityTypeManager(),
 );
@@ -61,7 +61,7 @@ Instead of doing this manually, let's start using mocks.
 
 Add `use Drupal\Core\Entity\EntityTypeManagerInterface;` and create a mock to use instead of the manually created version.
 
-```php
+```language-php
 $repository = new PostNodeRepository(
   $this->createMock(EntityTypeManagerInterface::class),
 );
@@ -73,7 +73,7 @@ As the mock implements `EntityTypeManagerInterface`, this will fix the failure,
 
 Next, try to get the posts from the Repository:
 
-```php
+```language-php
 $repository->findAll();
 ```
 
@@ -87,7 +87,7 @@ For the test to work, this needs to be mocked too and returned from the `getStor
 
 Create a mock of `EntityStorageInterface`, which will be used as the node storage:
 
-```php
+```language-php
 $nodeStorage = $this->createMock(EntityStorageInterface::class);
 ```
 
@@ -95,7 +95,7 @@ Next, this needs to be returns from the mock `EntityTypeManager`.
 
 To do this, specify that the `getStorage()` method when called with the value `node`, will return the mocked node storage:
 
-```php
+```language-php
 $entityTypeManager = $this->createMock(EntityTypeManagerInterface::class);
 $entityTypeManager->method('getStorage')->with('node')->willReturn($nodeStorage);
 
@@ -112,7 +112,7 @@ You'll need to use a mock for each node and set what each method needs to return
 
 The same as the Kernel test, set a title for each post with different created times.
 
-```php
+```language-php
 $node1 = $this->createMock(NodeInterface::class);
 $node1->method('bundle')->willReturn('post');
 $node1->method('getCreatedTime')->willReturn(strtotime('-1 week'));
@@ -131,7 +131,7 @@ $node3->method('label')->willReturn('Post three');
 
 Then, specify the `loadByProperties` method should return the posts.
 
-```php
+```language-php
 $nodeStorage->method('loadByProperties')->willReturn([
   $node1,
   $node2,
@@ -141,7 +141,7 @@ $nodeStorage->method('loadByProperties')->willReturn([
 
 Finally, add some assertions that the nodes returned are the correct ones and in the correct order:
 
-```php
+```language-php
 $posts = $repository->findAll();
 
 self::assertContainsOnlyInstancesOf(NodeInterface::class, $posts);
@@ -166,7 +166,7 @@ This is testing the same thing as the kernel test, but it's your preference whic
 
 Hopefully, if you run your whole testsuite, you should see output like this:
 
-```plain
+```language-plain
 PHPUnit 9.6.15 by Sebastian Bergmann and contributors.
 
 .........                                                           9 / 9 (100%)
@@ -176,7 +176,7 @@ Time: 00:07.676, Memory: 10.00 MB
 
 Or, if you use `--testdox`, output like this:
 
-```plain
+```language-plain
 PHPUnit 9.6.15 by Sebastian Bergmann and contributors.
 
 Blog Page (Drupal\Tests\atdc\Functional\BlogPage)
diff --git a/source/_pages/atdc/2.md b/source/_pages/atdc/2.md
index f2e12077..9a22067c 100644
--- a/source/_pages/atdc/2.md
+++ b/source/_pages/atdc/2.md
@@ -22,7 +22,7 @@ For example, how do we test the administration pages to see if they work for a u
 
 Let's start with a new test:
 
-```php
+```language-php
 public function testAdminPageLoggedIn(): void {
   $this->drupalGet('/admin');
 
@@ -47,7 +47,7 @@ This is commonly known as the **Arrange** step of the test.
 
 To create a user, use `$this->drupalCreateUser()` and `$this->drupalLogin()` to log in as that user.
 
-```php
+```language-php
 $user = $this->drupalCreateUser();
 
 $this->drupalLogin($user);
@@ -61,7 +61,7 @@ As we're testing against a temporary Drupal installation, we don't have access t
 
 To do this, when creating the user, include an array of permissions to add to it:
 
-```php
+```language-php
 $user = $this->createUser(permissions: [
   'access administration pages',
   'administer site configuration',
@@ -80,7 +80,7 @@ Let's create a page and test we can view it.
 
 Firstly, let's ensure the page is not found:
 
-```php
+```language-php
 public function testContent(): void {
   $this->drupalGet('/node/1');
   $this->assertSession()->statusCodeEquals(Response::HTTP_NOT_FOUND);
@@ -91,7 +91,7 @@ Similar to `$this->createUser()`, there are similar methods to create content ty
 
 Again, as there are no existing content or content types, we need to create them and add the follow-up assertions:
 
-```php
+```language-php
 public function testContent(): void {
   // ...
 
@@ -111,7 +111,7 @@ You're probably expecting the test to pass now, but you'll likely get an error l
 
 To fix this, we need to tell Drupal to enable the `node` module within the test by adding this within the test class:
 
-```php
+```language-php
 protected static $modules = ['node'];
 ```
 
@@ -123,7 +123,7 @@ Here's a tip for today: if you're getting an unexpected status code or another e
 
 To do that, add this to your test, and it will output the page content:
 
-```php
+```language-php
 var_dump($this->getSession()->getPage()->getContent());
 ```
 
diff --git a/source/_pages/atdc/3.md b/source/_pages/atdc/3.md
index 6f434b7e..89c55f07 100644
--- a/source/_pages/atdc/3.md
+++ b/source/_pages/atdc/3.md
@@ -20,7 +20,7 @@ Create a new `BlogPageTest` and have it extend `BrowserTestBase`.
 
 Let's assert that a page should exist at `/blog` by returning a `200` status code, as this should be accessible by anonymous users.
 
-```php
+```language-php
 <?php
 
 namespace Drupal\Tests\atdc\Functional;
@@ -49,7 +49,7 @@ Whilst you could create the page using the Views module, let's create a custom r
 
 Create an `atdc.routing.yml` file:
 
-```yaml
+```language-yaml
 # web/modules/custom/atdc/atdc.routing.yml
 
 atdc.blog:
@@ -65,13 +65,13 @@ With this added, the status code doesn't change and is a `404`.
 
 Like in the previous lesson, you need to enable the `atdc` module by setting `$modules` in your test:
 
-```php
+```language-php
 protected static $modules = ['atdc'];
 ```
 
 You'll also need to create an `atdc.info.yml` file so the module can be installed:
 
-```yaml
+```language-yaml
 # web/modules/custom/atdc/atdc.info.yml
 
 name: ATDC
@@ -81,7 +81,7 @@ core_version_requirement: ^10
 
 This should change the status code to a `403`, as you also need the `node` module for the `access content` permission:
 
-```php
+```language-php
 protected static $modules = ['node', 'atdc'];
 ```
 
@@ -97,7 +97,7 @@ Let's do that next.
 
 Create the expected Controller class within a `src/Controller` directory:
 
-```php
+```language-php
 <?php
 
 // web/modules/custom/atdc/src/Controller/BlogPageController.php
@@ -115,7 +115,7 @@ For this step, the simplest thing you can do to get a passing test is to return
 
 As long as it's an array, even an empty one, the test should pass:
 
-```php
+```language-php
 public function __invoke(): array {
   return [];
 }
@@ -131,7 +131,7 @@ This is also a good time to do a `git commit`.
 
 Again, let's start with a new test:
 
-```php
+```language-php
 public function testPostsAreVisible(): void {
   // Arrange.
   $this->createNode(['type' => 'post', 'title' => 'First post']);
@@ -165,7 +165,7 @@ Start by extending the `ControllerBase` base class within your Controller:
 
 Now, within the `__invoke` method, add this to return a list of each node title:
 
-```php
+```language-php
 public function __invoke(): array {
   $nodeStorage = $this->entityTypeManager()->getStorage('node');
   $nodes = $nodeStorage->loadMultiple();
diff --git a/source/_pages/atdc/4.md b/source/_pages/atdc/4.md
index 4a287f52..d3cccbe4 100644
--- a/source/_pages/atdc/4.md
+++ b/source/_pages/atdc/4.md
@@ -26,7 +26,7 @@ This will contain the `PostNodeRepository` class that will be responsible for lo
 
 Add this as the initial content:
 
-```php
+```language-php
 <?php
 
 namespace Drupal\atdc\Repository;
@@ -62,7 +62,7 @@ $nodes = $nodeStorage->loadMultiple();
 
 Add them to the `findAll()` method, alter the first line that gets the `EntityTypeManager` (we'll refactor this later) and return the loaded nodes:
 
-```php
+```language-php
 public function findAll(): array {
   $nodeStorage = \Drupal::entityTypeManager()->getStorage('node');
   $nodes = $nodeStorage->loadMultiple();
@@ -73,7 +73,7 @@ public function findAll(): array {
 
 Within the `BlogPageController`, create a constructor method and inject the Repository using constructor property promotion:
 
-```php
+```language-php
 public function __construct(
   private PostNodeRepository $postNodeRepository,
 ) {
@@ -82,7 +82,7 @@ public function __construct(
 
 Add `use Drupal\atdc\Repository\PostNodeRepository;` if needed, and use it to load the post nodes:
 
-```php
+```language-php
 
 public function __invoke(): array {
   $nodes = $this->postNodeRepository->findAll();
@@ -105,7 +105,7 @@ Currently, the test is failing, as the response code is a `500` status because t
 
 It's expected within the constructor, but you must add a `create` method to inject it.
 
-```php
+```language-php
 public static function create(ContainerInterface $container): self {
   return new self(
     $container->get(PostNodeRepository::class),
@@ -123,7 +123,7 @@ To do this, create an `atdc.services.yml` file within your module.
 
 Add `PostNodeRepository` using the fully-qualified class name as the service name:
 
-```yaml
+```language-yaml
 services:
   Drupal\atdc\Repository\PostNodeRepository:
     arguments: []
@@ -139,7 +139,7 @@ Before moving on, let's refactor the `PostNodeRepository` and inject the `Entity
 
 The same as the `BlogPageController`, create a constructor method and inject the `EntityTypeManagerInterface`:
 
-```php
+```language-php
 public function __construct(
   private EntityTypeManagerInterface $entityTypeManager,
 ) {
@@ -148,7 +148,7 @@ public function __construct(
 
 Add the `use Drupal\Core\Entity\EntityTypeManagerInterface;` if needed, and specify it as an argument so it's injected into the constructor:
 
-```yaml
+```language-yaml
 services:
   Drupal\atdc\Repository\PostNodeRepository:
     arguments:
diff --git a/source/_pages/atdc/5.md b/source/_pages/atdc/5.md
index 62ed07a1..97334a91 100644
--- a/source/_pages/atdc/5.md
+++ b/source/_pages/atdc/5.md
@@ -28,7 +28,7 @@ Instead of making HTTP requests and checking the responses, we can test the resu
 
 Let's create a new test that uses the `PostNodeRepository` to find the nodes and assert we get an expected number returned.
 
-```php
+```language-php
 <?php
 
 namespace Drupal\Tests\atdc\Kernel;
@@ -73,7 +73,7 @@ It's defined within `atdc.services.yml`, but we need to be explicit about which
 
 Create a `$modules` array within the test class and add `atdc`:
 
-```php
+```language-php
 protected static $modules = ['atdc'];
 ```
 
@@ -83,7 +83,7 @@ Run the tests again, and you should get a different error:
 
 As well as `atdc`, you must enable the `node` module. You can do so by adding it to the `$modules` array:
 
-```php
+```language-php
 protected static $modules = ['node', 'atdc'];
 ```
 
@@ -111,7 +111,7 @@ Within the test, you can use `$this->createNode()` to create posts.
 
 Create the three posts the test is expecting:
 
-```php
+```language-php
 // Arrange.
 $this->createNode(['type' => 'post']);
 $this->createNode(['type' => 'post']);
@@ -126,7 +126,7 @@ Next, let's assert they're returned in a specific order.
 
 Update the posts to have a specific title and created date so we can specify which order we expect them to be returned in and which titles they should have:
 
-```php
+```language-php
 // Arrange.
 $this->createNode([
   'created' => (new DrupalDateTime('-1 week'))->getTimestamp(),
@@ -151,7 +151,7 @@ Note we're intentionally setting them to be in an incorrect order, to begin with
 
 Next, assert that the titles are returned in the correct order.
 
-```php
+```language-php
 self::assertSame(
   ['Post two', 'Post one', 'Post three'],
   array_map(
@@ -165,7 +165,7 @@ For each node in `$nodes`, get its label (title) and compare them with the title
 
 As expected, the test fails:
 
-```plain
+```language-plain
 1) Drupal\Tests\atdc\Kernel\PostNodeRepositoryTest::testPostsAreReturnedByCreatedDate
 Failed asserting that two arrays are identical.
 --- Expected
@@ -187,7 +187,7 @@ We need to update the code within `PostNodeRepository` to fix the ordering.
 
 After loading the nodes, we need to sort them.
 
-```php
+```language-php
 public function findAll(): array {
   $nodeStorage = $this->entityTypeManager->getStorage('node');
   $nodes = $nodeStorage->loadMultiple();
@@ -206,7 +206,7 @@ This gets us further, but the test is still failing.
 
 Whilst the order is correct, the array keys don't match what we expect:
 
-```plain
+```language-plain
 1) Drupal\Tests\atdc\Kernel\PostNodeRepositoryTest::testPostsAreReturnedByCreatedDate
 Failed asserting that two arrays are identical.
 --- Expected
@@ -233,7 +233,7 @@ And, because the correct titles are still being shown, our original Functional t
 
 Tip: to see the names of the tests in your output, add the `--testdox` flag to the `phpunit` command:
 
-```plain
+```language-plain
 Blog Page (Drupal\Tests\atdc\Functional\BlogPage)
  ✔ Blog page
  ✔ Posts are visible
diff --git a/source/_pages/atdc/6.md b/source/_pages/atdc/6.md
index 585bc7c6..06f47e34 100644
--- a/source/_pages/atdc/6.md
+++ b/source/_pages/atdc/6.md
@@ -12,7 +12,7 @@ In yesterday's lesson, you created your first Kernel test and used it to ensure
 
 This is how we're creating the posts currently:
 
-```php
+```language-php
 $this->createNode([
   'created' => (new DrupalDateTime('-1 week'))->getTimestamp(),
   'title' => 'Post one',
@@ -40,7 +40,7 @@ Let's create a Builder class to create the posts.
 
 This is how I'd like to create a post using a `PostBuilder`:
 
-```php
+```language-php
 PostBuilder::create()
   ->setCreatedDate('-1 week')
   ->setTitle('Post one')
@@ -51,7 +51,7 @@ This makes it easier to do by creating named methods for each value we want to s
 
 To do this, create a new class at `src/Builder/PostBuilder.php`:
 
-```php
+```language-php
 <?php
 
 // web/modules/custom/atdc/src/Builder/PostBuilder.php
@@ -73,7 +73,7 @@ As it returns a new version of `self`, you can also chain methods onto it.
 
 Add the additional methods and properties:
 
-```php
+```language-php
 private ?DrupalDateTime $created = NULL;
 
 private string $title;
@@ -95,7 +95,7 @@ Again, by returning `$this`, we can keep chaining methods.
 
 Finally, create the `getPost()` method that creates the node based on the property values, saves it, and returns it.
 
-```php
+```language-php
 public function getPost(): NodeInterface {
   $post = Node::create([
     'created' => $this->created?->getTimestamp(),
@@ -111,7 +111,7 @@ public function getPost(): NodeInterface {
 
 Now, refactor the test to use the `PostBuilder`:
 
-```php
+```language-php
 PostBuilder::create()
   ->setCreatedDate('-1 week')
   ->setTitle('Post one')
@@ -136,7 +136,7 @@ Finally, for today, let's refactor the assertion that verifies the titles are re
 
 This is the current assertion:
 
-```php
+```language-php
 self::assertSame(
   ['Post two', 'Post one', 'Post three'],
   array_map(
@@ -152,7 +152,7 @@ We can make this more reusable and readable by extracting this into a new custom
 
 Create a new static function at the bottom of the class with a name that describes what it's asserting:
 
-```php
+```language-php
 /**
  * @param array<int, string> $expectedTitles
  * @param array<int, NodeInterface> $nodes
@@ -179,7 +179,7 @@ The benefits are that this now has a name that describes what we're asserting, a
 
 Finally, refactor the test to use the new assertion:
 
-```php
+```language-php
 self::assertNodeTitlesAreSame(
   ['Post two', 'Post one', 'Post three'],
   $nodes,
diff --git a/source/_pages/atdc/7.md b/source/_pages/atdc/7.md
index 200a178c..2d45a36d 100644
--- a/source/_pages/atdc/7.md
+++ b/source/_pages/atdc/7.md
@@ -20,7 +20,7 @@ First, let's ensure that only published nodes are returned and displayed on the
 
 We can do this easily with a functional test, so add a new test method to `BlogPostTest`:
 
-```php
+```language-php
 public function testOnlyPublishedNodesAreShown(): void {
   PostBuilder::create()
     ->setTitle('Post one')
@@ -54,7 +54,7 @@ In this test, we want to create some published and unpublished posts and assert
 
 To fix the error, add this function so it exists:
 
-```php
+```language-php
 public function isPublished(): self {
   return $this;
 }
@@ -70,7 +70,7 @@ When using `PostBuilder` in the previous lesson, we were always providing a crea
 
 Update the `getPost()` method to only set the created time if the `created` property has a value.
 
-```php
+```language-php
 public function getPost(): NodeInterface {
   $post = Node::create([
     'title' => $this->title,
@@ -93,7 +93,7 @@ Now, we can see a similar error to the one before for `isNotPublished()`.
 
 Again, create the simplest version of the method so the test can progress:
 
-```php
+```language-php
 public function isNotPublished(): self {
   return $this;
 }
@@ -112,13 +112,13 @@ Within `PostBuilder`, we need to use the `isPublished` and `isNotPublished` meth
 
 First, add an `isPublished` property to the class and set it to be `TRUE` by default:
 
-```php
+```language-php
 private bool $isPublished = TRUE;
 ```
 
 Next, update the `isPublished()` and `isNotPublished()` methods to set the value appropriately:
 
-```php
+```language-php
 public function isNotPublished(): self {
   $this->isPublished = FALSE;
 
@@ -136,7 +136,7 @@ Even though `isPublished` is already true by default, doing this makes it explic
 
 Finally, within `getPost()`, update the code that creates the node to set the `status` property accordingly.
 
-```php
+```language-php
 $post = Node::create([
   'status' => $this->isPublished,
   'title' => $this->title,
@@ -152,7 +152,7 @@ We also need to update the `PostNodeRepository` as that is responsible for loadi
 
 Currently, all we're doing is this:
 
-```php
+```language-php
 $nodes = $nodeStorage->loadMultiple();
 ```
 
@@ -160,7 +160,7 @@ This will load all nodes, regardless of their type or status.
 
 To fix this, change this to use `loadByProperties()` instead:
 
-```php
+```language-php
 $nodes = $nodeStorage->loadByProperties();
 ```
 
@@ -170,7 +170,7 @@ Note: you can also use `->getQuery()` if you prefer and write the query yourself
 
 For this case, let's add a property for `status` and its value to be `TRUE`:
 
-```php
+```language-php
 $nodes = $nodeStorage->loadByProperties([
   'status' => TRUE,
 ]);
@@ -184,7 +184,7 @@ The other issue is all published nodes are returned, even if they aren't posts.
 
 Before adding this to `PostNodeRepository`, create a new failing test for it:
 
-```php
+```language-php
 public function testOnlyPostNodesAreShown(): void {
   PostBuilder::create()->setTitle('Post one')->getPost();
   PostBuilder::create()->setTitle('Post two')->getPost();
@@ -213,7 +213,7 @@ If you run the test, it should fail as expected:
 
 Now we have a failing test, let's add the extra condition to `PostNodeRepository`:
 
-```php
+```language-php
 $nodes = $nodeStorage->loadByProperties([
   'status' => TRUE,
   'type' => 'post',
diff --git a/source/_pages/atdc/8.md b/source/_pages/atdc/8.md
index 9a16a9b2..591e189f 100644
--- a/source/_pages/atdc/8.md
+++ b/source/_pages/atdc/8.md
@@ -12,7 +12,7 @@ In this lesson, let's add tags to our posts using the `PostBuilder`.
 
 As we're doing test-driven development, start by creating a new `PostBuilderTest`:
 
-```php
+```language-php
 <?php
 
 // web/modules/custom/atdc/tests/src/Kernel/Builder/PostBuilderTest.php
@@ -37,7 +37,7 @@ Let's start by testing the existing functionality within `PostBuilder` by verify
 
 Create these tests, which should pass by default as the code is already written:
 
-```php
+```language-php
 /** @test */
 public function it_returns_a_published_post(): void {
   $node = PostBuilder::create()
@@ -73,7 +73,7 @@ Next, create a test for adding tags to a post.
 
 It should be mostly the same as the others, but instead of an assertion for the published status, try to use `var_dump()` to see the value of `field_tags`:
 
-```php
+```language-php
 /** @test */
 public function it_returns_a_post_with_tags(): void {
   $node = PostBuilder::create()
@@ -104,7 +104,7 @@ The convention is to create a test module that will only be required within the
 
 To do this, create a `web/modules/custom/atdc/modules/atdc_test` directory and an `atdc_test.info.yml` file with this content:
 
-```yaml
+```language-yaml
 name: ATDC Test
 type: module
 core_version_requirement: ^10
@@ -123,7 +123,7 @@ Rather than trying to write them by hand, I create the configuration I need, suc
 
 To do that for this project, as I'm using the PHP built-in web server, I can use Drush to install Drupal using an SQLite database:
 
-```plain
+```language-plain
 ./vendor/bin/drush site:install --db-url sqlite://localhost/atdc.sqlite
 ```
 
@@ -143,7 +143,7 @@ These are the files that I created in my module based on the field I created.
 
 `field.field.node.post.field_tags.yml`:
 
-```yaml
+```language-yaml
 langcode: en
 status: true
 dependencies:
@@ -174,7 +174,7 @@ field_type: entity_reference
 
 `field.storage.node.field_tags.yml`:
 
-```yaml
+```language-yaml
 langcode: en
 status: true
 dependencies:
@@ -198,7 +198,7 @@ custom_storage: false
 
 Then, enable the module within `PostBuilderTest`:
 
-```php
+```language-php
 protected static $modules = [
   // Core.
   'node',
@@ -210,7 +210,7 @@ protected static $modules = [
 
 Finally, install the configuration to create the field. Add this within the test:
 
-```php
+```language-php
 $this->installConfig(modules: [
   'atdc_test',
 ]);
@@ -218,7 +218,7 @@ $this->installConfig(modules: [
 
 After adding this and attempting to install the configuration to add the field, you'll get an error:
 
-```plain
+```language-plain
 Exception when installing config for module atdc_test, the message was: Field 'field_tags' on entity type 'node' references a target entity type 'taxonomy_term', which does not exist.
 ```
 
@@ -234,7 +234,7 @@ As well as the field configuration, we also need to create the Post content type
 
 This can be done by creating a `node.type.post.yml` file:
 
-```yaml
+```language-yaml
 langcode: en
 status: true
 dependencies: {  }
@@ -255,7 +255,7 @@ Let's update the test and add assertions about the tags being saved and returned
 
 Get the tags from the post and assert that three tags are returned:
 
-```php
+```language-php
 $tags = $node->get('field_tags')->referencedEntities();
 self::assertCount(3, $tags);
 ```
@@ -264,7 +264,7 @@ As none have been added, this would fail the test.
 
 Update the test to use a `setTags()` method that you haven't created yet:
 
-```php
+```language-php
 $node = PostBuilder::create()
   ->setTitle('test')
   ->setTags(['Drupal', 'PHP', 'Testing'])
@@ -277,7 +277,7 @@ You should get an error confirming the method is undefined:
 
 To fix this, add the `tags` property and `setTags()` method to `PostBuilder`:
 
-```php
+```language-php
 /**
  * @var string[]
  */
@@ -297,7 +297,7 @@ Tags will be an array of strings, and `setTags()` should set the tags to the `ta
 
 Next, add the logic to `getPost()` to create a taxonomy term for each tag name.
 
-```php
+```language-php
 $tagTerms = [];
 
 if ($this->tags !== []) {
@@ -322,7 +322,7 @@ If `$this->tags` is not empty, create a new taxonomy term for each one and save
 
 As well as asserting we have the correct number of tags, let's also assert that the correct tag names are returned and that they are the correct type of term.
 
-```php
+```language-php
 self::assertContainsOnlyInstancesOf(TermInterface::class, $tags);
 foreach ($tags as $tag) {
   self::assertSame('tags', $tag->bundle());
@@ -333,7 +333,7 @@ To assert the tags array only includes taxonomy terms, use `self::assertContains
 
 Next, add some new assertions to the test to check the tag names match the specified tags.
 
-```php
+```language-php
 self::assertSame('Drupal', $tags[0]->label());
 self::assertSame('PHP', $tags[1]->label());
 self::assertSame('Testing', $tags[2]->label());
diff --git a/source/_pages/atdc/9.md b/source/_pages/atdc/9.md
index 9d9fb719..9897c866 100644
--- a/source/_pages/atdc/9.md
+++ b/source/_pages/atdc/9.md
@@ -22,7 +22,7 @@ I've also seen Unit tests that are very tightly coupled to the implementation, s
 
 Based on what you've learned so far, let's write a Unit test that we'd expect to pass:
 
-```php
+```language-php
 <?php
 
 namespace Drupal\Tests\atdc\Unit;
@@ -58,7 +58,7 @@ Update the test to create a mock version of `NodeInterface` instead.
 
 As the mock an instance of `NodeInterface`, it satisfies the assertion and the test passes.
 
-```php
+```language-php
 /** @test */
 public function it_wraps_a_post(): void {
   $node = $this->createMock(NodeInterface::class);
@@ -69,7 +69,7 @@ public function it_wraps_a_post(): void {
 
 Next, add an assertion to ensure the bundle is correct:
 
-```php
+```language-php
 self::assertSame('post', $node->bundle());
 ```
 
@@ -81,7 +81,7 @@ Because you're using a mock, all methods will return `NULL`.
 
 To get this to pass, you need to define what `$this->bundle()` will return:
 
-```php
+```language-php
 $node->method('bundle')->willReturn('post');
 ```
 
@@ -97,7 +97,7 @@ Within the test, instantiate a new `Postwrapper` class that takes the node as an
 
 Then, add an assertion that a `getType()` method should return `post`.
 
-```php
+```language-php
 $wrapper = new PostWrapper($node);
 
 self::assertSame('post', $wrapper->getType());
@@ -105,7 +105,7 @@ self::assertSame('post', $wrapper->getType());
 
 Next, create a `PostWrapper` class with the `getType()` method:
 
-```php
+```language-php
 <?php
 
 namespace Drupal\atdc;
@@ -132,7 +132,7 @@ We've tested that the `PostWrapper` works with post nodes, but let's also ensure
 
 Create a new test that creates a mock node and returns `page` as the bundle:
 
-```php
+```language-php
 /**
  * @test
  * @testdox It can't wrap a page
@@ -153,7 +153,7 @@ Before creating a new `PostWrapper`, assert that an `InvalidArgumentException` s
 
 To fix it, within the constructor for `PostWrapper`, check the bundle and throw the expected Exception if the bundle is not `post`:
 
-```php
+```language-php
 /**
  * @throws \InvalidArgumentException
  */