You can ignore all the previous stuff I said about pseudo elements etc. as I thought you were talking about something else not related to the front page.
Line 775 has the background color….it’s set to orange at the moment. If you want it to be slightly transparent you **can’t** use opacity there are it will affect everything in the [a] link including the text.
You will only have to change the background color to something like
where the 0.5 number is the amount of opacity you want on that color.
That’s the only thing you need to change.