Different color themes in Laravel 5.6/Bootstrap 4.1.0 application

In my laravel 5.6 / vue.js 2.5.7/ Bootstrap4.1.0 application I want to set different color themes and I found this collection https://github.com/thomaspark/bootswatch But how correctly to set them to my project? I tried to replace files

node_modules/bootstrap/dist/css/bootstrap.css
node_modules/bootstrap/dist/css/bootstrap.min.css

and cleared cache and rerun

npm run watch-poll

But no effect... Which is the right way?

Are there some tools to change color themes programmatically, say depending on logged user options ?

Adding a link of one bootswatch file in my layout file resources/views/layouts/app.blade.php, like:

<link href="" rel="stylesheet"> 

I see that colors of my layout of my pages is different, but I mean that in this case I ADD this css/darkly/bootstrap.min.css file to the EXISTING(ORIGINAL) bootstrap.min.css and now I have 2 bootstrap.min.css files in my system. Is it good decision? I supposed that creators of bootswatch meant to REPLACE the original bootstrap.min.css file. How do you think?

And that is the question where original Bootstrap css(and bootstrap.js to) are attached to the project ?

in my layout file resources/views/layouts/app.blade.php a line:

that is a ref to my custom css file, the styles I add to the project.

I did not find how to skip attaching of the original Bootstrap CSS file...

Thanks!

via Chebli Mohamed