In my sharepoint framework (No JavaScript Framework) project I know I can use CSS in the following ways:
Right at the beginning in the imports section:
There is the SCSS standard
import styles from './WebPart.module.scss';
Reference to css the solution
require('style library/css/File.css')
Reference to external css (I don't know if I can reference internal css this way with SPComponentLoader.loadCss)
SPComponentLoader.loadCss("https://site/bootstrap/css/bootstrap.min.css");
Inside onInit
SPComponentLoader.loadCss("https://site/bootstrap/css/bootstrap.min.css");
or (Use a css file from your own sharepoint site)
SPComponentLoader.loadCss("https://site.sharepoint.com/sites/site/Documents/file.css");
Or even in the HTML file like this
<link rel="stylesheet" type="text/css" href="" />
What would be the best way, or whatever?
Thank you