Modern way to create php website?

Question

I am seeking a way to use/incorporate more modern tech to our front end stack at work.

Our pages always follow this flow:

landing -> shipping -> payment -> receipt

they are all php files and getting a product names and such from backend. for a frontend, it is very old school HTML/CSS( SASS )/jQuery stack.
Another thing to note is that we provide very similar design pages to different clients so parts of the page can be reused. For example, a payment form can be shared between 10 different projects with different color scheme/logo/verbiage. We use php include for sharable components for now.

I was wondering if there's any modern alternative to create our pages while meeting these requirements:

• Need to be able to use in .php files
• Light weight since page load speed is one of the most important factor in this industry
• Has to follow the flow shown above
• Can turn into components to be reused in different projects( component library using Vue or React? )

I'd like to go more modern way even if it's an overkill.

Thanks in advance for your advise!

Edit: by "modern tech", I mean something that's being talked about and gaining popularity as of 2019. This includes frameworks, preprocessor and such.

Answer 1

Mustache

Consider Mustache it is a templating system. It allows the back end to emit structured data (such as json), and the front end to convert it to html using a template. There is a little more work in the back-end, middle, but less in the front-end.

CSS

css can be used for the style, logos, etc. You can have two style sheets, one common, and another from a set (one for each client).

Conclusion

If done well, you can separate: data storage (Database), data processing (output JSON), document structure (Mustache/HTML), style (CSS), layout (CSS).