Adding css file suitecrm8

i am so new in suitecrm8, i want to add some css styles, but i could not found and document for Suitecrm8.
how i can add css or scss files?

I copied
and added line <link rel="stylesheet" type="text/css" href="themes/suite8/css/rtl.css"> just before </head> tag.
I can add css rules to rtl.css file and it works.
Is it OK?
what is the best practice for adding css to suitecrm8?

only works on home.
In index.html in dist folder, always load dist/styles.d2fb070cfa28fe10bad3.css file.