I have made it work by putting directly @import "slim-select/dist/slimselect.css" into application.tailwind.css.
Another question I have is I want to render html under index page, but right now after applying the code I only render json. How to make both work HTML and json?
class CategoriesController < ApplicationController def index @categories = Category.where("name like ?", "%#{params[:query]}%") render json: @categories.map { |c| { value: c.id, text: c.name } } end end