What are common pitfalls when setting path references in PHP files, especially when using CSS frameworks?

Common pitfalls when setting path references in PHP files, especially when using CSS frameworks, include not properly specifying the correct path to the CSS file or images, leading to broken styles or missing images. To solve this, it is important to use the correct file path relative to the PHP file location or use absolute paths for more consistent referencing.

// Example of setting a correct path reference to a CSS file using PHP
<link rel="stylesheet" type="text/css" href="<?php echo get_template_directory_uri(); ?>/css/style.css">