If you're really into icon fonts, which I have recently become, you may have noticed a tiny storm brewing in the suburbs of the internet. It's about CSS-specified font smoothing. Quite a nichy topic, one you can live a perfectly good life without ever knowing all about. You may in fact sleep better by not reading on.
Still here? Alright, here's the deal. WebKit — born of Safari, engine of Chrome — allows webdevelopers to specify how the edges of fonts are smoothed. The modern default font smoothing method is called subpixel antialiasing. It smoothes font edges using quite impressive means, and in nearly all cases it drastically improves the rendering of letters. If you look at the text in a magnifying glass, though, you'll notice a nearly imperceptible blue haze on the left side of each letter, and a red haze on the right side. WebKit provides a means for webdevelopers to pick which type of font smoothing is applied: subpixel-antialiasing, antialiasing, or none. Handy. Right?
The controversy is the fact that a number of people — smart people — feel that this CSS property is damaging to the readability of text on the web. There are very long articles on the topic. In fact quite recently a Google employee removed the CSS property from Chrome, citing the notion that the browser should render text according to the operating system. There's just one problem: icon fonts.
Icon fonts are custom-made webfonts that contain no letters, only icons. The purpose is to have fast access to a bunch of icons in a very lightweight and easy way in your webdesigns. Other benefits include the fact that the icons are infinitely scalable because they're vector graphics, and you can easily apply any color, drop-shadow or even a gradient to each icon using plain CSS. Sounds brilliant, doesn't it?
The only downside is that an icon font is still technically a font, so the computer thinks each icon is actually a letter, and by default will try to subpixel antialias it. While subpixel antialiasing does wonders to letters, it'll fuzzy up your icons and make them look blurry. Which is why the
-webkit-font-smoothing property was so welcome. Here's an icon font without and with subpixel antialiasing:
As you can imagine, I'm strongly in favor of not only keeping the font-smoothing property, but in fact expanding it beyond WebKit to both Firefox and Internet Explorer. Icon fonts won't be a truly viable webdesign technique until every icon looks great on all the platforms.
"But SVG is the future of vector graphics on the web, surely you know that!" — Yes I do. But pragmatically speaking, that future is not here yet. SVG support is still lacklustre, especially when used as CSS backgrounds. More importantly, you can't easily change the color of an SVG icon using CSS only, or apply a drop-shadow. Yes, drop-shadows are on the road map for SVG, but the way it'll happen is not pretty. Icon fonts, on the other hand, provide a real-world solution today, which is both flexible and infinitely scalable. So next time you see someone bad-mouthing -webkit-font-smoothing, pat them on the head and mention icon fonts. The more you know.