For items that are unavailable (disabled), I am using the 'disabled' element. (as anybody else)
It's my personal choice/preference that such unavailable elements are barely visible/readable.
It's on purpose.
There are situations where an element is not 'unavailable' but is some sort of secondary header.
But it will get the colouring of a disabled element.
Like here, where 'Snelzoek afkortingen' (sorry, I'm in the process of translating) is some sort of secondary header, but since it's getting rendered as a 'disabled' element it's hardly readable:
So the request/suggestion here is to have a new element for such static/passive elements so they can be coloured to better indicate their unique function.