Advice on adding gradients to an existing theme

Hi, I need some pointers - in the right direction - the easiest way I can make minor modifications to custom themes.
In Mint 18.1, I modified the gtk-3 part of a stock theme, but I’m having a harder time getting the gtk-2 theme to (fairly) closely match the gtk-3 appearance.

So I downloaded & installed a gtk 2/3 theme, Cinnamox-Heather (a blue theme) to see how they handled gradients & such in gtk-2. By now, I’ve read plenty on creating / modifying gtk-2 themes. I’m most familiar w/ the murrine engine. I’ve had “moderate” success changing or enabling its features.

Part of the problem is lack of “real” understanding of what takes precedence in gtk-2.
For an existing theme, if I want to add gradients to scrollbar trough (whether using defined colors or specify different ones), or gradients to the toolbar, menu bar, or different color gradient to scrollbar slider, should I make the changes in the theme’s gtkrc, or in ~/.gtkrc-2.0?

I assume if they don’t already have gradients (or have a style I don’t like) I’ll have to comment their style & either add a gradient or use the theming engine’s gradient?

I’ve also noticed in some examples, after they enter a style for an object, directly under the style they list a widget or class to apply it, but on many other styles they don’t list anything under them.

Or are they listing several styles, one after another, then below them list the necessary class(es) or widget_class(es) that apply to the several styles, above?

Thanks.

You’re better tweaking the source rather than patching the theme on your ~/.gtkrc-2.0

Common practice is to associate the styles to the widgets at the end of the file, maybe that’s why on some sites it doesn’t show up.