Editing Line Height

[allopenstar]

Hi,

I am using the layout Brittle, and I am interested in changing the line height of the text, especially the main body text. How would I go about doing this? Where would I be able to find the source code so that I can edit it? Is there a way where I can edit without touching the source code?

I have no experience in using CSS at all, so any amount of help is greatly appreciated. Thanks!