Link code html into html

hello everyone !!
how can i link multi code html into just one code ?

Can you explain what you mean in a bit more detail?

i want to link html code into another one ;
i make a navbar and i want to link a theme to the background of this navbar.

As far as I know, I don’t think it’s possible with pure html but you can do it with PHP for sure.

You can import multiple CSS stylesheets in a page. Is that what you mean?

no i want to link html file to another .

so let us get this straight, you have a navbar made in html text file for one site, that you want to re create on another?

why not just copy and pasta the html text?

no i have a navbar in file and a theme in another file , i want to add the theme to the navbar .

Can you post the code of all the files you have so far, so we can have a better understanding?

I originally understood that you had a navbar in an html file and you wanted to import that in the body of another html file.