Space after a CSS code

Hi all,

I’ll try to be brief:
I’m trying to change something using Custom CSS. With “inspect” i found that the Class is called: “portfolio_description “.
Note that there is a Empty SPACE after the code before “.
I tried the following in Custom CSS: .portfolio_title {display:none;}

It did not work. I guess it’s because of the empty space.
How can I work with this code ?

I hope that this Topic is clear enough for you guys to understand what im struggling with. English is not my first language.

Thanks in advance,

kazlaga