As a front-end developer I always have the same problem when I need to define my font-sizes and line-heights in my CSS. Normally I need to take in consideration the base-size of the font to create the sizes of my h-elemnts and add to the equation the line-hight which needs to be proportional. And when all that is in place I go to bed whishing that the customer don’t change the font-type.
Well, to avoid that problem I strongly recommend you type-scale.com.
At type-scale you can choose the font family and base-size and the page will calculate for you the headers and pragraphs sizes and line-heights. You can also choose between different scales i.e. minor third, major third, augmented and a lot more.
Not enough whith that, type-scale generate a CSS-script that can be used in your CSS file with all sizes and line-heights.