@yeroentje:
Welcome! Glad you're enjoying the skin!
DISCLAIMER: When I started to write you a response, I inadvertently veered off to writing a much more complicated elaboration.
There's no way I can deal with this on a system level, simply because the combinations are endless, and there really isn't a way for Kodi to distinguish between colour types or values. To do it in a seamless fashion, I'd either have to completely limit the colour palette and work around it, or invent a system or algorithm by which to distinguish light and dark colours in Kodi. The first would needlessly complicate things and decrease usability, and I have no clue how to do the second one.
However, not all is lost! The skin was built with customisation in mind. You can solve this yourself by making your own colour theme. Basically, themes are only constant colour values defined in separate xml files located in the "colours" folder in the skin. Those values are then reused extensively in the skin. Here's a primer on the main functions of colour constants:
Code:
"Background" - Background Colour
"FanartFade" - ?
"HomeBarBG" - Home menu background
"HomeBarFG" - Home menu highlight
"HomeBarTile" - Widget tile background
"HomeWidgetBG" - Widget posters background
"DialogBG" - Dialogue background colour
"Highlight" - Primary Highlight
"Highlight2" - Secondary Highlight
"Selected" - Focused item colour
"MainLabel" - Main Label colour (Clock, the big name in the left corner, etc)
"SubLabel" - Sub Label colour (stuff like the date under the clock)
"HomeSubLabel" - Like the Sub Label, but on the Home page
"LineLabel" - Info Labels colour
"SideArrow" - RSS text colour
"PosterBorder" - Poster Focus frame
"ListLabel" - List Item colour
"Disabled" - Colour used to distinguish disabled items in the skin
"ObjectBackground" - Helps with the skin background panels
"ColorPicker" - Something for the CDArtManager add-on
Now, an important thing to state is that some of these colours can be set up inside the skin, while others can't and probably never will. The reason for that is simple. I could, for example, try to add all those settings to get some kind of switch, but that would mean implementing it manually for every possible view, introducing half a dozen new skin strings, and making the configuration infinitely more complex. However, for the enthusiast, there is still the option to mod/create your own theme.
I would recommend modifying the existing theme file and creating a copy of it rather than creating your own because there have been bugs with third colour schemes that I've not been able to fix, that are not present when either of these two is used. So in order not to introduce bugs due to a third theme, I'd recommend you make your modification in the theme upon which you base your use on, and paste it over after every skin update. Or simply try and create a theme, the bugs might not appear.
With the colour schemes, you can practically create a whole new user experience, albeit with a lot of tweaking and patience. The
dedicated theme thread for the skin might provide some inspiration. Be mindful that some posts in the thread are old, so you can't just copy-paste. The thread is great to find ideas for cool colour combinations that you can manually modify to use in the mod, using the primer above to match the colours to their respective functions.
Now, based on everything I've babbled about previously, the best solution to your query would be to change one of the existing theme files with the colours you would like to see. To be specific, the "Selected" colour value is what you need in this case. If you are using the default colour scheme, go to the defaults.xml, and change the default colour "fff0f0f0" to "bf181818", every time you focus an item, it will be a nice dark grey colour.
