Importing older themes, only partially?

Tried to import this Simple Windows 10 Dark Theme - #51 by stk_cg theme and it feels like importing of colors applied only partially.

1. This is supposed to happen, because whole coloring thing got overhauled?
Thought that I will easily switch to new color palette, oh boy how I was wrong.

Seems like if user is in Default Dark, importing doesn't change anything, but once you hop into Default Light, import, and don't switch to Dark when prompted, you get theme applied.
Partially but still.

2. Will there be any drawbacks for future me if I apply colors in such way?
Looks like this will be wrong approach, where rest of app remains Light, and I'm coloring certain pieces.

Think best option for me to find all these colors, it's to run v12 on main machine, and try v13 on VM for example.
Had to revert to v12 because few screens I made, didn't covered a lot of tiny details.
Never thought how NOT dark, was Legacy dark theme. So many tooltips and all sort of hints...

Loading that theme works fine here. The colors aren't that different to the default dark colors, but they definitely change slightly.

It also shouldn't matter if you're in dark or light mode before loading the theme. If you're in dark mode, it'll be applied to dark mode. If you're in light mode, Opus will detect that the old theme is probably meant for dark mode and ask you if you want to switch modes first:

Hmm, in my case it wasn't working as I expected on main machine.
While when tried on VM, I got actually pleasing result.

Not creating another topic, as next question can be sort of related.
Nitpicking? Sure.

When DarkER theme is imported, few pieces were missing, and I assume this is because now theming now is more detailed. So I tried to match an adjusted few pieces here and there.

Can someone help me to find setting which color these "sides" of column header?
Column is one color, but on sides color is different.

If this got removed in V13, then sure this doesn't needs to be implemented. We would survive without that for sure.

Preferences / Colors and Fonts / Windows Colors / Headers

  1. Default v12 with DarkER theme.
  2. v13 with imported theme (Border - Inner, were disabled) ((maybe I adjusted these weeks ago, cant be sure))
  3. When Inner are enabled.
  4. The color adjusted on Inner.
    It seems that in v12 inner are only on sides, but in v13 it's on all sides.
    Could be I'm wrong, and surely people will find combo that does it as shown in first screen.
    After experimenting, now the 4th image looks good for me. =)