CSS automatically linked to HTML with Rails - ruby-on-rails

Question

I created a style.css file in app/assets/stylesheets for my Ruby on Rails project. I added some styling and started up the server. I didn't put any <link href...> or stylesheet_link_tag anywhere in any html.erb file but every page had the css changes I wrote in style.css
Additionally, I now have to restart the server every time I make a change to the CSS in order to see those changes in the browser. Has anyone ran into this before? By the way, I am using action cable. I also don't have a public/assets folder.
application.js
require("#rails/ujs").start()
require("turbolinks").start()
require("#rails/activestorage").start()
require("channels")
require("jquery")
$(document).on('turbolinks:load', function () {
alert("Hello!");
})
application.css
/*
* This is a manifest file that'll be compiled into application.css, which will include all the files
* listed below.
*
* Any CSS and SCSS file within this directory, lib/assets/stylesheets, or any plugin's
* vendor/assets/stylesheets directory can be referenced here using a relative path.
*
* You're free to add application-wide styles to this file and they'll appear at the bottom of the
* compiled file so the styles you add here take precedence over styles defined in any other CSS/SCSS
* files in this directory. Styles in this file should be added after the last require_* statement.
* It is generally better to create a new file per style scope.
*
*= require_tree .
*= require_self
*/
style.css
table{
border-collapse: collapse;
}
table, th, td{
border: 1px solid black;
}
#left, #right {float:left}
#left {width: 30%;}
#right {width: 70%;}