If you want more of it, then try to Play with Inspect (To grab sections manually) or View page source option to get hands-on it. Simply Google search to get possible Info on both options, how to use and why.
You can only get the HTML, CSS and JavaScript you can’t get the php,node, etc because that language runs on server not your browser so whatever that your browser render is HTML, CSS and JavaScript the php is server side so there is no chance that that code will be sent to your browser. So conclusion is that you can only get HTML, CSS and JavaScript files.