Hi,
I would like to change the opacity of the question container (se in attach) and make it partially transparent, so the background image could be seen.
How can I do it?

Thank you!

Hi,
if you use a webdeveloper tool that is included in each modern browser, you will see that there are two classes involved.

.question-title-container
.question-valid-container

In your extended theme set their opacity to the desired value in "custom.css".

something like
Joffm

By the way:
If you want the opacity for the whole question, (title, validation, answer and help)
it is just

Tank you.