Rectangle shade in slider with captions

Hello!

I’m having a problem with my slider and I can’t find the solution to it.
When I activate the slider captions, there is a rectangle grey shade that appears over the image. I’m OK with the rectangle that appears where the caption text is, but I don’t want the other shade to appear because it does not look good with the image below.

That rectangle does not appear when I hide the captions, so, is there a way to eliminate it while leaving the captions?

Here’s my site: http://anglo.edu.py/wp/

It isn’t finished yet, so you might find unfinished stuff.

By the way, is there a way to change the color of the rectangle appearing in the slider text, it is green now and I will change my site’s colours so I might want to change that too.

Thanks a lot!

Yas