Who knows that fonts are responsive, even before the current rage of responsive design ? Well, I certainly did not know. Until now. Responsive Typography for fonts are called font hinting. It has existed way back since the beginning of printing.
The concept of responsive font itself is similar to the current responsive design. How to make the font appears the same when it scales.
The fundamentals of hinting
Type and web designers usually think of “hinting” as instructions built into digital fonts to improve their rendering on a grid of pixels. Hinting pushes the points of a font’s Bézier curves around according to contextual conditions, such as the font’s rendering size. Though it’s now associated with type on screens, hinting was first used in the 1980s to improve rendering on low-resolution printers.
Thinking about it in these terms, hinting is responsive type that existed before the web: The font performs a media query of sorts to learn its size, then responds by repositioning points in each glyph according to built-in instructions, or “hints.”
In other words, hinting is to fonts what responsive layout is to websites. It allows a single font file to adapt to a variety of contexts, the same way CSS allows a single HTML file to adapt to a variety of contexts. In fact, Håkon W. Lie used the term “presentation hints” in 1994 to summarize his original proposal for CSS.
Source: A List Apart
Upon further reading into A List Apart “Font Hinting and the Future of Responsive Typography“, apparently this problem is still largely unsolved today. So, it is possible that responsive design will also suffers the same fate. It is good for some problems, but cannot fix all problems.
It is an interesting read, nonetheless. I would suggest you read it for reference. Once you do, you are welcomed to come back and leave a comment in this website.