How to implement efficient code splitting in PHP programming for website assignments?

How to implement efficient code splitting in PHP programming for website assignments? I have come to a real understanding of SASS, and implementing its functionality is as easy as passing some html to a css selector. I found using some sample code, sass-simple-scss [class*=scss] This works for the custom search of websites that users write them [class*=scss] of use. But I implemented it with only the css selector. with css .class*@class/body for