How can we speed up icon fonts and fix these issues? This layout shift causes a negative User expereince and is an important factor in the Google Core Web Vitals.
When the fonts is loaded and rendered the page style needs to be recalculated causing the lay-out to shift. Icon fonts will always cause a layout shift.That CSS file blocks loading and causes a delay in the LCP and FCP. A large, render blocking CSS file is needed for an Icon Font because all letters have to be 'mapped' to an icon in yiour stylesheet.Usually we would like to avoid this flash of invisible text but that is not possible with web fonts. After the font has been loaded the icons appears on the page. A browser will not know how to deal with this because it has no system icons fonts available.īecause there is no substitute font available, the space for the icon remains empty during page load. There is no point in substituting an icon font. Normal fonts can be replaced with a substitute system font while loading.Why not? That's because Icons Fonts behave just a little different the normal WebFonts. Unfortunately, we can't use most of the clever tricks I describe there for Icon Font. In the article Smart WebFont loading for better performance, I discuss a number of strategies to improve WebFont performance. The default behavior of the CSS file is to block loading of the page. To add to that, webfonts also use a CSS file to 'map' the fonts. This creates a small (or large) layout shift on your page. That is why the browser continues building the page and as soon as the font has been downloaded, the icons are painted on the screen. WebFonts are loaded anly when a font glyph is visible on the page (to be specific, the glyph must be used in a visible TextNode). WebFonts can get in the way of loading a page. įor now it is important to remember that, in order for WebFonts to work, you need to download not only a CSS file but also a WebFont file. In font awesome you can, for example, use to display a gear icon. The fonts are accessed through CSS classes. Instead of using separate images, all icons are combined in one single WebFont file. What they all have in common is that a trick is applied. Some are gigantic like font-awesome and offer webmasters access to over 5000 icons while others are a bit smaller like Weather Icons. There are many different of Icon Fonts in circulation. Font awesome loaded from CDN without modification Font awesome lazy loaded What are font icon sets?
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