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Ensure text remains visible during webfont load

Ensure text remains visible during webfont load

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Appears in: Performance audits

Fonts are often large files that take awhile to load. Some browsers hide text until the font loads, causing a flash of invisible text (FOIT).

How the Lighthouse font-display audit fails #

Lighthouse flags any font URLs that may flash invisible text:

A screenshot of the Lighthouse Ensure text remains visible during webfont loads audit

See the Lighthouse performance scoring post to learn how your page's overall performance score is calculated.

How to avoid showing invisible text #

The easiest way to avoid showing invisible text while custom fonts load is to temporarily show a system font. By including font-display: swap in your @font-face style, you can avoid FOIT in most modern browsers:

@font-face {
  font-family: 'Pacifico';
  font-style: normal;
  font-weight: 400;
  src: local('Pacifico Regular'), local('Pacifico-Regular'), url(https://fonts.gstatic.com/s/pacifico/v12/FwZY7-Qmy14u9lezJ-6H6MmBp0u-.woff2) format('woff2');
  font-display: swap;
}

The font-display API specifies how a font is displayed. swap tells the browser that text using the font should be displayed immediately using a system font. Once the custom font is ready, it replaces the system font. (See the Avoid invisible text during loading post for more information.)

Preload web fonts #

Use <link rel="preload" as="font"> to fetch your font files earlier. Learn more:

Google Fonts #

Add the &display=swap parameter to the end of your Google Fonts URL:

<link href="https://fonts.googleapis.com/css?family=Roboto:400,700&display=swap" rel="stylesheet">

Browser support #

It's worth mentioning that not all major browsers support font-display: swap, so you may need to do a bit more work to fix the invisible text problem.

Try it! Check out the Avoid flash of invisible text codelab to learn how to avoid FOIT across all browsers.

Stack-specific guidance #

Drupal #

Specify @font-display when defining custom fonts in your theme.

Magento #

Specify @font-display when defining custom fonts.

Resources #

Last updated: Improve article