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Mozilla Firefox 62 Brings Dark Theme on macOS, Variable Fonts and More

MMS Founder

Article originally posted on InfoQ. Visit InfoQ

Mozilla has released Firefox 62. This version brings variable fonts, automatic dark theme on macOS Mojave, improved scrolling on Android, and more.

Firefox 62 for desktop brings support for Variable Fonts. Variable Fonts are an evolution of the OpenType font specification that enable many different variations of a typeface to be incorporated into a single file. Standard fonts usually require a separate font file for each variation, resulting in more HTTP requests, and more data being downloaded (around 20k per file). Variable Fonts contain additional data, enabling developers to access all variation contained in a given font file via CSS and a single @font-face reference.

Variables Fonts are supported for Edge 17+, Firefox 62+, Chrome 69+, Chrome for Android 69+, Safari 12+, and Safari for iOS 11.4+ browsers. It is important to notice that Linux needs the latest Linux Freetype version, and macOS prior to 10.13 does not support variable fonts.

(image taken from the

This is how you can use variable fonts in a CSS file::

@font-face {
  font-family: 'AmstelvarAlpha';
  src: url('../fonts/AmstelvarAlpha-VF.ttf');
  font-weight: normal;
  font-style: normal;

Another new feature, exclusive to macOS, is that Firefox will now automatically enable the dark theme when macOS Mojave is in dark mode.

Firefox 62 for desktop brings a series of new features, changes, and removals for web developers, such as:

Firefox 62 also brings a series new features, changes, and removals for add-on developers:

Other new features, bug fixes and changes not related specifically for developers are:

  • A preference that allows users to distrust certificates issued by Symantec, removing all trust for Symantec-issued certificates in Firefox 63. To use this preference, go to about:config in the address bar and set the preference “security.pki.distrust_ca_policy” to 2. It is related to a series of questionable website authentication certificates issued by Symantec Corporation’s PKI
  • FreeBSD support for WebAuthn (Bug 1468349)
  • Improved graphics rendering for Windows users without accelerated hardware using Parallel-Off-Main-Thread Painting (Bug 1454980)
  • Support for CSS Shapes, allowing for richer web page layouts. This goes hand-in-hand with a brand-new Shape Path Editor in the CSS inspector
  • Adobe Flash applets now run in a more secure mode using process sandboxing on macOS
  • A change to how WebRTC handles screen sharing: when screen-sharing a window, the window will be brought to the front (Bug 1450658)

The complete list of features, bug fixes and changes in Firefox 62 can be found in the release notes. Furthermore, there is a site compatibility guide for Firefox 62.

Firefox for iOS has received some tab improvements, allowing users to search, switch and manage tabs. Now it is possible to manage tab settings in a single view. Furthermore, users will be able to search their open tabs and seamlessly switch between normal and private browsing.

Another new feature available on Firefox for iOS is that now users can easily change the theme from dark to light, manually or automatically: to do so click on “Settings > Display > Light or Dark”, or automatically turn it on by using the Automatic switch.

Firefox for Android has received a series of security fixes, and some performance improvements, including:

  • Improved scrolling performance
  • Faster page load times over WiFi connections by loading from the network cache if disk cache is slow
  • “Product and feature tips” toggle in Notifications settings, allowing for more control over which notifications are shown
  • WebRTC video sessions between Firefox for Android and Safari browsers work again

Users who already have Firefox installed should be able to upgrade it automatically; new users can download Firefox 62 for desktop on Both android and iOS users can download from Google Play and Apple’s App Store.

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