How to make classes invisible in the stylesheet

Can you tell me how to make classes invisible in the stylesheet?

I'm doing it like this 

.links

{

display: none;

}

 and as a result, the links class, which consists of two objects (buttons), disappears.

 But I only need to remove one button 

.0 first

{

display: none;

}

 Due to the fact that there is a space after 0 in the class, I can't access it. 

Can you suggest how to resolve this? You can see everything in the image.