Hi @MRog40. What exactly is your use case? Do you want to change styles in time, let’s say a Sunday style on Sundays, a Monday style on Mondays, and a Fancy style when you just feel happy? Or do you want different kind of notes to have their own permanent style?
For changes in time, you could — as a setup — create a collection of userstyle-«xxx».css files, one for each style, and henceforth copy the one that’s most suitable at some period to userstyle.css, followed by the F5 trick as mentioned by @CalebJohn. I would recommend to write a script (or a set of scripts) for the copy action, in order to reduce the risk of overwriting the wrong CSS file at distracted moments.
Giving a specific note a different permanent style can be done in various ways. Two suggestions here.
1
By including a style block in the note (on top, at the bottom, it doesn’t matter where exactly) that imports the demanded CSS file, e.g.:
<style>html
@import url(C:/Users/memophen/.config/joplin-desktop/userstyle-fancy.css);
@import url(/Users/memophenon/.config/joplin-desktop/userstyle-fancy.css);
</style>
The first URL is valid on my pc, the second is valid on my iMac (I had chosen different user names on these platforms, so I need two lines now). Regrettably relative addresses like userstyle-fancy.css or ~/.config/joplin-desktop/userstyle-fancy.css don’t work. Be aware that the style definitions in userstyle.css are still operational as far as they are not explicitly overwritten by userstyle-fancy.css.
2
By classifying the entire content of the note:
<div class="fancy">
... Content of note goes here ...
</div>
This approach comprehends the specification of separate sets of all involved style elements, one set for each particular note-level class (sunday, monday, fancy, …), and all sets collected in that one and only userstyle.css, since included @imports are ignored by Joplin.