[Solved] How CSS personnalisation works ?

[EuchChinge]

Hi

I'm trying to make some appearence changes with CSS at this page :
https://boardgamearena.com/preferences?section=advanced

I've tried this simple modification :

h2{
color: red;
}

And the same code with the HTML tag style. But it didn't work.

I've tried to add a JS comment in order to see if the field area was made for JS instructions, but the field area content has been erased.
I've also tried to load an external CSS file, with the head tag, without any change.

Is this feature working ?

Thanks

[EuchChinge]

I wish to have this kind of presentation (30 lines of code including some hover things) :

[EuchChinge]

It has been "solved" here :
https://boardgamearena.com/bug?id=14908