Customising the Arduino IDE theme colours? (not pre-made themes)

Searching for guides or advice on this topic seems very limited, and most of it is scattered around quite a bit.

To simply change the colour(s) of variables, for example. I assumed that changing the “fg” hex value for the style token “VARIABLE” within dark.xml, and default.xml, within Arduino\lib\theme\syntax would update the syntax highlighting, but had no luck.

Is there simply a step (or a few) that I’m missing? Also I’m sorry if this may be a duplicate post

Thanks in advance, and also any other Arduino IDE theme customisation tips are very welcome!

Forum member @coffeeguy published a nice tutorial on using Arduino IDE themes earlier this week:

That tutorial provides instructions for the ".zip file installation" installation method for themes. Since you're interested in customizing themes, which makes the .zip file a bit less convenient, you might prefer the "Direct installation" installation option I provide instructions for here:

One important thing to note is that you need to restart the Arduino IDE before changes to the theme files will take effect.

Other than those installation instructions, everything I know about custom Arduino IDE themes is documented here:

Luucccc:
changing the "fg" hex value for the style token "VARIABLE" within dark.xml, and default.xml

dark.xml isn't used at all by the Arduino IDE. It only uses default.xml. If you prefer a dark theme, you can rename dark.xml to default.xml. There are also some more full featured dark themes from members of the community, a couple of which are in that tutorial I linked above.

Thankyou very much for the references pert, I didn't realise that most of the styling can be done within theme.txt. To style elements such as brackets, and numbers you must modify colours within default.xml which is odd.

But I'm unable to find the styling for binary formatted values such as 0b10101010, which remains black

EDIT 16/06/2022:
After finally wanting to fix this annoyance, and despite there probably being a more updated way of styling things.
You can style binary numbers by setting the values of:

<style token="ERROR_IDENTIFIER" fg="eb7cd9" />
<style token="ERROR_NUMBER_FORMAT" fg="eb7cd9" />
<style token="ERROR_STRING_DOUBLE" fg="eb7cd9" />
<style token="ERROR_CHAR" fg="eb7cd9" />

within Program Files (x86)\Arduino\lib\theme\syntax\default.xml

You're welcome. I'm glad if I was able to be of assistance.

Luucccc:
To style elements such as brackets, and numbers you must modify colours within default.xml which is odd.

It is odd. default.xml was introduced in arduino IDE 1.6.5 when they switched to using RSyntaxTextArea for the Arduino IDE's editor. Before that the IDE theme was only controlled by the properties in theme.txt. Some of those theme.txt properties I documented as "Doesn't appear to have any effect" may be leftovers that did have an effect when using with Arduino IDE 1.6.4 and older.

Note that all the properties in default.xml control the editor theme. You might expect the opposite would be true with theme.txt: that it only controls the theme of the GUI, but this is not the case.

Luucccc:
But I'm unable to find the styling for binary formatted values such as 0b10101010, which remains black

I did a quick check and also couldn't find a theme property to control that. If you do find it, please let me know.