Background transparent

Hi.

I tried to find information by myself and I found nome bot nothing work well.

I have 2 questions actually. If I do a CSS website by myself I can do it but it seems a little bit more difficult with WordPress.

So, basically, I have my page. The main backbround is a picture and … I see a big white square in the midle … the content zone.
Normally I’m very ok with that but for 1 page I need to have a content background perfectly transparent.
I found that on internet”

.transparent {
filter: alpha(opacity=40);
-moz-opacity:.40;
opacity:.40;
}

I added that im my custom CSS and associate it with my page. It’s working well exxcept that even my text and button are also transparent … And for sure I want to see them clearly…

I tried to make another class with opacity at 99 for my text and button but it doesnt work.

Im on Theme forest X.
If you have any idea i’ll be very happy

thx a lot