Increase line height in Post title / Widgets

Hello, I added some custom CSS to decrease the line height of the blog post body text, but in the process, have applied this to all of the text on the theme. This is no problem, however, the title on blog posts are squashed when they're more than one line. I'm keen to increase the line height on the blog post title and also between each item inside the widgets - a wider gap between each Tweet, for example. Could someone advise on the best way to do this? My website is http://www.creativeunderground.co.uk Many thanks.