ERPNext 15 CSS theme not loading


I have tried numerous ways to load a CSS file in ERPNext 15 and have had no luck.
Are these instructions still valid.

  1. Modify to have app_include_css = “/assets/flash/css/flash.css” where flash is the name of my custom app.

  2. Have my css file as frappe-bench/apps/flash/flash/public/css/flash.css

  3. Have a build json file called build.json in frappe-bench/apps/flash/flash/pubic folder with {
    “css/flash.min.css”: [

  4. bench build --app flash

and yet the css file is not loaded. I also created a script below to make sure it would be forced to load, but the css file still is not loading.

cd ~/frappe-bench
bench build --app flash
bench build
bench --site all migrate
bench --site all clear-cache 
bench --site all clear-website-cache 
bench --site clear-website-cache
bench restart
bench --site all enable-scheduler

Has ERPNext 15 gone way from the CSS customization or is there a new way to install CSS files in ERPNext 15. Some help (or a updated manual) would be very beneficial as most the information seems to be over two years old. I don’t like the idea of having to hard code a .js file to do the colours and design on each field of my custom app.

Please check the reference. Review the process and how it is defined in the custom app.