Redesign website to be responsive

I have an existing site that wasn't expressly built to be responsive. I would like make some design changes that work on all device sizes. Also I would prefer to stay within Bootstrap or Tailwinds and not have to rely on a bunch of custom css files.
The site is written in Laravel and Vue but it's not imperative that you know these. I can convert the html/css code to work within the project if needed.