Chapter 6. Be Progressive: Font Sizing and FOUT

In this chapter we’re going to talk about two important aspects of being responsive with your type: sizing it appropriately and getting it on screen fast. While we covered absolute speed in the last chapter, in this one we’re going to tackle perceived speed, which ultimately may be more important. We’ll also look at a key aspect of the notion of Progressive Enhancement. Essentially, it’s planning for failure. You must design and code your site with the assumption that there will always be some point during the loading process or viewing experience when web fonts will not be present—and handling that appropriately is essential. By designing and developing for the brief moments before web fonts load, you’re also addressing the (potentially) millions of visitors to your site for whom web fonts won’t load at all (i.e., those browsing via Opera Mini).[3]

On Units of Measure

There are lots of choices in sizing type, but if you’re looking to be most compatible with modern web design and development techniques, a relative unit of measure is extremely important. Rather than using a fixed unit of measure (px), you’ll want to use em or rem (cleverly meaning a relative em).

I tend to stick with ems because if you base your text sizes, vertical margins and padding, and media query ...

Get Responsive Typography now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.