Upon an external style sheet rule modification, the respective resource text is updated in the Resources panel, and the revision history is stored for such style sheet resources until the DevTools window is closed. Activate the Resources panel, find tutorial.css in the resource tree. Note that the tree node is expandable. Your first option is to build the page like a normal HTML web page with HTML tags, but instead of stopping there, use separate PHP tags to wrap up the PHP code. You can even put the PHP code in the middle if you close and reopen the <?php and ?> tags.
Importing External Style Sheets. The @import rule is another way of loading an external style sheet. The @import statement instructs the browser to load an external style sheet and use its styles. You can use it in two ways. The simplest way is to use it within the <style> element in your <head> section. A style is a set of formatting characteristics that are defined in a cascading style sheet (CSS) and define how to display HTML elements. You can apply styles to content in a web page, including text (individual characters or entire paragraphs), graphics, layers, tables, and even to the body of the entire web page.