Reduce line spacing

Hi everyone

I’m working on a website built with the Twenty Fifteen theme and usual Visual Composer (or WP Bakery Visual Builder as it’s now known). The problem is that the customer wants the line spacing smaller. I used the Shift-Enter trick but the two lines are still too far apart (specifically the “headers” above the content in the Home Page). It’s worth mentioning that they are NOT H1 and H2 at the moment, I used Paragraph with custom font sizes for both in order to try to make the space smaller, but I still can’t get the space between the two lines small enough.
When I use the “Inspect Element” function in Firefox I see that the line-height is 1.6842. When I change this to 1.2 in Inspect Element it goes to the right size, but I can’t change this in custom CSS or even edit it in the style.css file itself, it makes no difference. In fact, in the style.css there is no line-height that is 1.6842, the only thing that comes close is under Body, and it says 1.6471. Does anyone have any idea where and how I can change this?

The page I need help with: [log in to see the link]