Post title too narrow when viewed from a phone

I’ve recently noticed that the title and excerpt text of all posts isn’t showing properly when viewed from a mobile phone, though it’s fine on a desktop/laptop.

If you view the url: http://www.thevisualbloq.com on a mobile phone, you’ll see what I mean – on my iPhone 5 it’s pretty much showing just one or two words per line.

How do I fix this?