What best practices should be followed when modifying the appearance of a PHP website?

When modifying the appearance of a PHP website, it is important to follow best practices to ensure the changes are made efficiently and effectively. One common practice is to separate the HTML markup from the PHP logic by using templating engines like Twig or Blade. This helps in maintaining clean and organized code. Additionally, using CSS frameworks like Bootstrap can help in creating responsive and visually appealing designs. Lastly, regularly testing the website on different browsers and devices is crucial to ensure a consistent user experience.

// Example of separating HTML markup from PHP logic using Twig templating engine

// Include the Twig Autoloader
require_once 'vendor/autoload.php';

// Specify the location of Twig templates
$loader = new \Twig\Loader\FilesystemLoader('templates');

// Initialize Twig environment
$twig = new \Twig\Environment($loader);

// Render a template with data
echo $twig->render('index.html', ['title' => 'My Website']);