How to embed the forum engine into the original website design?

Question

CMS

Tell me a lightweight forum engine in PHP only without a design design, roughly speaking, so that I can access it from the page, and I myself set the appearance of topics and messages through CSS. So that I could embed this small forum on a page on my site without breaking out of the design of my site

Answer 1

Did you mean: "How to embed the original website design into the forum engine" ?
Apparently, find a suitable forum and create a template for it.

Answer 2

Any open / free package comes with one or more themes, this is logical, people should see that something has worked out. All these topics are either corrected or new ones are installed.

Answer 3

In my theme I worked with the Vanilla forum in my opinion this is what you need:
1. Everything works out of the box
2. Integration into the existing site design is just elementary
3. Full of plugins that make life easier

Answer 4

As I understand it, ideally you want an ajax forum that can be embedded into an existing site. Like Ecwid for shops. I was looking for one like this and couldn't find it.
UPD. https://muut.com/