Best way to apply css to a set of notebooks/notes

I’m using Joplin to write notes in English (LTR) and Farsi (RTL). Currently, I add the following snippet at the beginning of my notes in Farsi to make it render properly:

@import url('');
body {
    direction: rtl;
    <!--font-family: 'Lateef', cursive;-->

I was wondering if there’s a simpler more convinient way of doing this in Joplin. I was thinking of maybe based on tags? For example, apply this style on notes with tag farsi.

No, the only way is to add it to your userstyle.css file, but in that case it will be applied to all notes.