Some notes about using web fonts

I just launched a new design for this site, and in this process I was particularly meticulous about my typographic choices.

These are a few of the things I learned.

Only use what’s necessary

This is somewhat obvious, but it’s still a fairly common mistake: you should only use and include the necessary fonts that make your design work.

There are several font families that use multiple styles and sometimes it’s tempting to use nearly all of them: normal, light, medium, bold, ultrabold, italic, bold italics… But you should remember that for every style, the user must download another file, and all of those bytes can add up to a painfully slow page load — which will make both your users and Google sad.

Try to avoid using an specific style for a single UI element, and remember that different families have very different file sizes.

Lastly, and even though it might be considered an abomination for typography nerds, remember that browsers can an usually will fake some basic font styles such as bold (simply thickening the “normal” style) or italics (with a slight slant).

Create a check-list with your requisites

The Google Fonts catalogue has over 700 font families; the full Typekit library over 1200. If you have enough time or are somewhat indecisive you can really go crazy before settling for the perfect fonts combo.

A good idea to help in your decision process it’s to create a check-list with all the requisites you need to fulfil, for instance:

  • The file weight for a single style must be less than 40 Kb (compressed)
  • The font family must have these styles: normal, bold, italic, bold italic
  • It must support non-english characters such as accented vowels
  • The normal style must be highly readable on small sizes

Changing your main font family on the middle of the design process can be a real pain: re-setting the body size and line height affects your entire design, so it’s a choice that must be carefully weighted.

Watch out for bugs

Fonts are not immune to bugs; watch out for thinks like:

  • Missing or erroneous characters: make sure you thoroughly test all the characters you need to support and check that all of them are shown correctly. For instance, when testing a font I found that the character for a typographic ellipsis looked like a single dot.
  • Variable heights on different styles: previous versions of the Roboto family had different heights on some of the styles, even when setting an explicit line-height. For instance, a single line of text using just the normal style showed the expected line-height, but when using a single (or more) bold characters, it increased the line-height. This was fixed on a newer version.
  • Hinting issues: when I decided to self-host the fonts for this site, I used FontSquirrel’s webfont generator to convert to the different formats required for each browser and further optimize the fonts by subsetting only the required characters. Even though I used previosuly hinted fonts, when I chose to Keep the existing hints the result looked awful on Windows, so instead I used the unhinted versions with TTFAutohint.

Many of the fonts available through Google Fonts are published on GitHub, so if you find a bug you could contact the developers and submit an issue, but it’s uncertain how long will it take for Google to update their version (which it’s in part why I’m self-hosting the fonts for this site).

Enable ligatures or other font features

After you finally made up your mind and chose the perfect fonts, make sure to show them in all of their glory.

Even though Firefox enables ligatures by default, Google Chrome and Safari don’t, so you need to explicitly activate them, like:

h1, h2, h3, h4, h5, h6{
    font-variant-ligatures: common-ligatures discretionary-ligatures;

There are plenty of other font features that you can control; check the font-variant docs on MDN to get a good overview.