If you ever wanted to test your page on different font sizes, body line height, etc … you can now do this using Gridlover. This is a free web application for establishing a type system with modular scale and vertical rhythm that you can build your project upon.
Basically, what Gridlover is doing is it keeps sizing type tidy and logical. Font sizes are calculated by stepping up the font size by the scale factor. If you visit their website you will notice a page that has major HTML tags for type (headings, lists, paragraphs, etc) that allows you to play with Gridlover. Main options that you can change are: body font size, body line height, scale factor, size of each element or the unit desired (px, em, etc). After playing with it and making your somehow desire page, you can see the outputs of the CSS rules that you can use.