Fonts that are not installed or embedded into the site can look different on different machines if that specific font is not installed. That's why it is best to use a font family when adding fonts in CSS. Bold Headline states in the style.css header that it uses Lato and Playfair Display from a href="http://www.google.com/fonts">Google Web fonts. Go to http://www.google.com/fonts, search for those fonts and click "Add to Collection". At the bottom, you should see the bar for collections. On the far right of that bar is the 'Use' button. Check the versions you want. Google fonts has a neat feature that lets you know how much these fonts will slow down your site. Because these fonts have a lot of of versions, you might want to pick and choose which ones you want.
After you have them selected, scrolling down will get you the html link code which you will need to input into the head tag of each php page. Then you can use the font family css below that to incorporate it into the CSS (which is already there, the fonts just need to be embedded).
Let me know if you need any more help with this.