Transparent calender items in Thunderbird

I am not the only person with this problem:
Something calendar entries in Lightning register as status Tentative and it shows in a different transparent shade of the calendar color. I can manually change the status to confirmed directly in lightning however that is a pain. Plus, it sounds crazy but having these entries a different shade/color drives me nuts.

Now see: for a way to deal with this… except of course, it is not the complete solution and only works after a slight modification. So what to do:

Add following css code to your userChrome.css file, mostly found at C:\Users\»your username«\AppData\Roaming\Thunderbird\Profiles\»some random letters«\chrome
If last folder and/or userChrome.css don’t exist, just create them.

Edit the file and add the following content:

agenda-richlist-item[invitation-status="TENTATIVE"] {
opacity: 1 !important;

That’s all folks! Good luck!
Any other questions? Contact My Brain!